Fluid management and measurement systems, devices, and methods

ABSTRACT

A medicament preparation system includes a disposable cartridge with a flow path. Various sensors may be placed on the cartridge to measure qualities of the fluid flowing through the flow path. The sensors are placed in precise locations using various approaches that make manufacturing of the cartridge efficient and repeatable. A drain line that is susceptible to fouling may be preattached and various approaches are used to remove or reduce the fouling. An elastomeric contact can also be present in the medical preparation system and used in a conductivity measurement subsystem.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage filing under 35 U.S.C.

371 of International Application No. PCT/US2018/039191, filed Jun.24,2018, which claims the benefit of priority to U.S. provisionalapplication No. 62/524,498, filed Jun. 24, 2017; U.S. provisionalapplication No. 62/524,490, filed Jun. 24, 2017; U.S. provisionalapplication No. 62/524,495 filed Jun. 24, 2017; and U.S. provisionalapplication No. 62/524,513 filed Jun. 24, 2017, all of which are herebyincorporated by reference in their entireties.

BACKGROUND

There are many types of blood processing and fluid exchange procedures,each providing different therapeutic effects and demanding differentprocessing criteria. Some procedures entail the removal of blood oranother fluid from an individual and the return of blood or anotherfluid to the individual in a controlled fashion. Other types use naturalbody tissues to exchange blood components with a medicament. Examples ofsuch procedures include hemofiltration (HF), hemodialysis (HD),hemodiafiltration (HDF), and peritoneal dialysis (PD). A commonrequirement of such procedures is the provision of large quantities ofmedicament such as dialysate that has a precise mixture of solutecomponents and is free of contaminants and pyrogenic materials.

Some known systems for preparing medicaments such as dialysate arecontinuous proportioning systems and batch mixing systems. Carrying outtreatment procedures using medicaments may employ special-purposemachinery. In the dialysis treatments listed above, devices calledcyclers are often used. These pump fluid and may also pump blood,depending on the treatment. In the process of pumping, they preciselyproportion the net amounts of fluid supplied and discharged and ensuresafety by various means including monitoring of pressure, temperature,leaks, and other treatment conditions. In principle, these treatmentsare relatively simple, but because of the need for patient safety andhealth outcomes, treatment procedures and treatment systems are complex.

Home delivery of these treatments raises concerns about safety andtreatment efficacy. One of the drawbacks of home treatment is the needfor a supply of purified water. In clinics, large reverse osmosis plantsprovide a continuous supply of purified water. In the home, such largesystems may not be practical because they require high volume of waterand drainage. Installing and using relevant components can be adifficult and expensive task and may require modifications to apatient's home. In addition, the systems for the production of properlymixed medicaments in pure form require a high level of precision andsafeguards as well as training and maintenance. To provide effective andsafe systems for home delivery of blood treatments, there is an on-goingneed for innovations in these areas and others. For example, PCTpublication number WO2016049542, which is incorporated herein byreference in its entirety, discloses a medicament preparation systemthat includes a water purification module and a medicament proportioningmodule, where the system is configured to allow convenient and safe usein a home environment or a critical care environment as well as othersaffording safety, reliability, and a compact form factor.

Some medical devices combine two or more substances to produce amedicament. One example is the preparation of dialysate for dialysis,where different fluids are mixed, such as a concentrated dialysate and adiluent such as water. It is desirable to control precisely the amountof the dialysate concentrate, or other fluids, as they are combined withthe diluent. In certain situations, uncontrolled or accidental mixingmay take place due to gravimetric action or due to pressure or vacuumcreated downstream in the fluid channel.

Many medical devices have portions that are replaced regularly and otherportions that replaced less frequently or are permanent. The latter maybe used repeatedly, depending on the application, for preparation oftreatment fluids or treatment with treatment fluids as well as otherapplications.

In some treatment systems or fluid preparation systems (genericallyidentified herein as fluid management systems) a common component is aportion of the fluid circuit that directs waste fluid to a drain. Suchcomponents can become fouled due to the repeated use. Examples of suchsystems include treatment devices, fluid preparation such as admixingdevices, and water purification systems.

A disposable medical device may benefit from the ability to accuratelymeasure conductivity or resistivity of a liquid. To this end, aconductivity sensor can be formed from two electrodes positioned at twolocations in a fluid chamber. A current is generated between theelectrodes with a current source as the voltage between the electrodesis measured. With knowledge of the size and shape of the volume betweenthe electrodes and the contact areas of the electrodes (sensordimensions) a “cell constant” can be calculated and used to calculatethe conductivity of the fluid. The cell constant can be measured for arepresentative sensor such that the sensor dimensions need not be knownexplicitly by calibrating using a fluid having known conductivity. Thedriving current and detected voltage are typically alternating to avoidsignal drift due to various known chemical and physical drivers.

The accuracy of the conductivity sensor is influenced by assurance ofconsistent sensor dimensional parameters. The latter include thephysical relationship between the two electrodes and their relationshipto the fluid volume defining the conduction path. Therefore, it isadvantageous to control the placement of the electrodes within thehousing of the conductivity sensor during the manufacturing process. Theconductivity sensor may be a part of a disposable medical component suchas a portion of a fluid circuit, where the manufacturing process mayconstrain the achievable manufacturing tolerances. These issues, andothers, are addressed by embodiments of the present disclosure. Summary

An elastomeric electrical contact is formed by a parallel array of wiressupported on an elastomeric block. The wires may span a relief formed ina side surface of the block. The wires may wrap over three sides of theelastomeric block and make contact with contacts in a silicone housing.The contacts in the housing may be, for example, on the side or on thebottom side opposite the top surface of the elastomeric block. Theelastomeric contact may be used in a replaceable component of amedicament preparation system to establish a reliable electricalconnection with a sensor in a permanent component of the medicamentpreparation system. The medicament preparation system may include awater purification module and a medicament proportioning module, and maybe configured to allow convenient and safe use in a home environment ora critical care environment as well as others, thus affording safety,reliability, and a compact form factor. The sensor may be a conductivitycell in which current and voltage measurement contacts are reliablyconnected, by way of the elastomeric contact disclosed herein, to wettedelectrodes in a replaceable component, so that the conductivity of afluid is measured accurately.

Generally, a compliant multiconductor element is positioned betweenmultiple terminal contacts that, whose function requires these multipleterminal contacts to make electrical contact by being forced against asingle electrode to contact it at different positions on the electrodesurface. The electrode element may be positioned at variable distancesfrom the multiple terminal contacts due to manufacturing variability oruncertain engagement by a user, creating a potential for a highresistance connection between the electrode and the multiple terminalcontacts. This may arise, in part, where the multiple terminal contactsa minor fraction of the size of the electrode such that a membercarrying both elements would have to be perfectly aligned with thesurface of the electrode in order for all of the multiple terminalcontacts to make sure electrical contact with the electrode. This isbecause one of the contacts may begin to resist the forcing againstbefore another of the multiple terminal contacts makes full electricalcontact with the electrode. That is, one of the multiple terminalcontacts, or a substrate carrying them, may “block” the another of themultiple terminal contacts from making full electrical contact with theelectrode. For example, but not limited to this example, one of themultiple terminal contacts is connected to a current source and theother one of the multiple terminal contacts is connected to a voltagemeasurement device. According to the disclosed subject matter, aresilient element with many flexible conductors running from one surfaceof the element to the opposite surface is positioned between themultiple terminal contacts forming a connection between each of themultiple terminal contacts and the single electrode. The number of theflexible conductors may be sufficient for there to be redundantconnections between each of the multiple terminal contacts and thesingle electrode. In that case, the redundancy can help ensure that ifsome conductors make incomplete contact with the electrode and arespective one of the multiple terminal contacts, the other may still doso. In the above arrangement, an electrode that is tilted relative tothe surface of the compliant multiconductor element or relative to thepath of closure between the multiple terminal contacts and theelectrode, the compliance of the compliant multiconductor element willprevent the blocking effect described above.

In the disclosed embodiments, the compliant multiconductor element ismated to a disposable device containing the electrode. A housing forms asealed connector that holds the compliant multiconductor element inplace adjacent the electrode. In embodiments, a conductivity cell withtwo electrodes are each provided with a housing and compliantmulticonductor element. A permanent excitation component (a device witha current source and a voltage measurement device to which a disposabledevice carrying the electrodes is attached) with multiple terminalcontacts to be electrically connected to each of the electrodes isengaged with the device carrying the electrodes by forcing themtogether. The housing holds the compliant multiconductor element on theelectrode. The compliant multiconductor element is thus used only forduration of the use of the disposable device and is advantageouslycarried by it. In alternative embodiments, the compliant multiconductorelement is attached to the permanent excitation component.

The general form of the compliant multiconductor element may be likethat of so-called zebra connectors. The zebra connectors are used toconnect a component with multiple contacts one-to-one to multiplecontacts. They are in the general category of electronic interconnectdevices. Designers employ them where a large number of very smallcontacts, for example a row of contact pads, each a fraction of amillimeter across, must be contacted with each other, the rows beingparallel and facing each other. Then the zebra connector can be placedbetween them rows and pressed together to cause the contacts to makeelectrical contact through the zebra connector conductors. A commonapplication example is connecting LCD panels. In the presentembodiments, the same type of zebra connector may be used in a devicehaving larger contacts, for example, ones that are more than amillimeter in size. The zebra connector may be used to connect a pair ofcontacts with a single electrode rather than corresponding contacts inone-to-one fashion. Also, the zebra connector is used in applicationswhere the contact strips are thin and known to be flexible requiring acompliant mechanism to form a sandwich to make the electrical contacts.In the present application of a single electrode connecting to a smallnumber of contacts, other solutions such as pogo pins or leaf springcontacts would generally be used.

Embodiments of the present disclosure provide conductivity sensor with ahousing that can be manufactured by various processes such as injectionmolding, casting, or extrusion, optionally combined with thermal ormechanical machining. The disclosed embodiments provide resistance tovariation in critical sensor dimensions due to manufacturing variabilitysuch as applied forces, quantities of cement, offsets in assembly ofcomponents, etc. In particular, the critical sensor dimension of theelectrode fluid contact area, position, and shape are preciselycontrolled with effective and reliable sealing of the electrodes to ahousing. It may be appreciated that while embodiments below are focusedon a conductivity sensor that includes an insertable electrode in anopening of a housing, the disclosure is also applicable to a multitudeof other applications where it is necessary to press, push, insert, orforce an object into an opening and obtain a repeatable and predictablefit within that opening.

It is desirable to precisely and repeatedly position an electrode withinopenings of a housing according to embodiments of the disclosure. Thehousing may define a flow channel for continuous monitoring ofconductivity of a flowing fluid. The housing may also be a vessel wherefluid is stored. Each electrode is positioned in an opening whose axialprofile (“axial” referring to a central axis of the opening connectingthe interior of the housing with the exterior along the most directline). The opening may have a stepped profile so that moving fromoutside to inside the housing, the area of the opening diminishes. Thatis, an outside portion of the opening has a larger diameter than aninside portion of the opening. The outside portion may include one ormore spacers that project radially inward but which do not extend acrossthe circumference of the opening inside portion. The inside portion mayhave a rim that extends axially toward the outside of the housing. Therim defines a trough. When an electrode is pressed into the outerportion it is over-constrained by the spacers which are the only partsin contact with the inserted electrode until the electrode lands againstthe rim to seal the opening fully. The placement of the spacers providesprecise centering of the inserted electrode within the opening, andminimizes deformation of the inserted electrode and the housing.Further, the spacers may have a shape that allows the electrode to bepressed in with force that is low, consistent, and uniform along alength of the traversal while confining the position of the electrode asit is pressed home. When the electrode reaches home, the resistanceforce is no longer frictional (or due to scraping of the spacers) butrather generated by interference caused by seating on the rim. Anassembly line robotic press can exploit the sudden rise in resistanceforce exerted to determine that the electrode has been fully insertedwhen the assembly line machine exerts a predetermined maximum force onthe electrode.

As the electrode is pressed into the opening of the housing, the spacersare physically deformed since the space for the electrode may be madeslightly smaller than the electrode. It is possible that a part or partsof the spacers may be scraped or shaved off to produce one or moreshaving or burrs. These may remain attached or break off when eachelectrode is pressed into an opening of the housing. To prevent anyshaving or burr from interfering with consistent placement of theelectrode, such shavings or burrs are received in a trough so that theycannot become trapped between the electrode and a final seating surfacedefined by the rim. Thus, any burrs or shavings can bend away or fallaway into the trough thereby leaving an arrest surface (e.g., the top ofthe rim) free of obstructions whereby the electrode is fully pressedinto its intended position, providing for highly precise positioning ofthe electrode within the housing.

Various embodiments of the present disclosure provide a medicamentpreparation system that includes a fluid circuit having fluid channelswith at least one junction, the junction joining a common flow channelthat leads from a water inlet to a medicament outlet. The junction maybe joined to a pumping tube segment connected to a source of medicamentconcentrate by a concentrate channel. The fluid circuit may be orientedin a predefined way relative to the force of gravity. The concentratechannel has a chicane that curves sharply up and sharply down before theconcentrate channel meets the common flow channel.

In embodiments, the chicane's length may be no greater than ten internaldiameters of the concentrate channel local to the chicane.

In embodiments, the chicane is immediately adjacent a point where thecommon flow channel and the concentrate channel meet.

In embodiments, the internal cross-sectional flow area of the chicane issmaller than that of the remainder of the concentrate channel.

In embodiments, the chicane is operable as a trap when fluid of a firstdensity remains in the concentrate channel while fluid of a seconddensity remains in the common flow channel at the junction, where thefirst density is higher than the second density, whereby gravitysiphoning is prevented.

In embodiments, the fluid circuit may be formed in a rigid structureand/or in a rigid cartridge.

In embodiments, an overhang may be present to reduce or prevent thediluent from entering the concentrate channel.

In embodiment, a flap that is biased in the closed position may bepresent in addition to, or instead of, the chicane. The flap bias forceis sufficient to prevent flow of the concentrate due to gravimetricaction, but the bias force is overcome when the concentrate is pumpedalong the concentrate channel to allow mixing with the diluent.

In embodiments, a gravity trap in a fluid path or fluid circuit reducesthe occurrence, or prevents, unintended mixing of fluids of differentdensities caused by gravimetric action. In an exemplary embodiment, thegravity trap can be included in an online dialysis proportioning systemthat prepares dialysate from a concentrate. In this example, the fluidsthat are admixed may be a dialysate concentrate and purified water, butother concentrates and diluents are envisioned. In an embodiment, one ofthe fluids is a mixture of purified water and bicarbonate, while theother fluid is an acid.

Objects and advantages of embodiments of the disclosed subject matterwill become apparent from the following description when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments will hereinafter be described in detail below with referenceto the accompanying drawings, wherein like reference-numerals representlike elements. The accompanying drawings have not necessarily been drawnto scale. Where applicable, some features may not be illustrated toassist in the description of underlying features.

FIGS. 1A and 1B show a contact issue that arises in connection withmultiple point electrode contacts for an article of manufacturecontaining an electrode which interfaces with a permanent multi-pointcontact element.

FIGS. 1C and 1D illustrate a mechanism for overcoming a contact issuethat arises in connection with multiple point electrode contacts for anarticle of manufacture containing an electrode which interfaces with apermanent multi-point contact element according to embodiments of thedisclosed subject matter.

FIG. 1E shows a compliant multiconductor element according toembodiments of the disclosed subject matter.

FIG. 2 shows an overview of an online system that includes a waterpurification module, proportioning medicament proportioning module, anda cycler forming an online treatment system, according to embodiments ofthe disclosed subject matter.

FIG. 3 shows details of the water purification module of the embodimentof FIG. 1, according to embodiments of the disclosure subject matter.

FIG. 4 shows an overview of an online water purification, proportioningmedicament generation, and treatment system, according to embodiments ofthe disclosed subject matter.

FIG. 5 shows details of an embodiment of medicament proportioningmodule, according to embodiments of the disclosed subject matter.

FIG. 6 shows further details of a fluid circuit cartridge according toembodiments of the disclosed subject matter.

FIGS. 7A through 7E show features of a conductivity and temperaturemeasurement cell that, according to embodiments, can be integrated inthe fluid circuit cartridge of FIG. 6 and others disclosed herein,according to embodiments of the disclosed subject matter.

FIGS. 8A through 8C show an arrangement of elements that show howelectrical, thermal, and mechanical engagement (contact) with sensorinstrumentation and actuated elements can be made according toembodiments of the disclosed subject matter.

FIGS. 9A and 9B show embodiments of a conductivity measurement componentthat may be used with any cartridge embodiments, or substituted withequivalent conductivity measurement components thereof in any of theembodiments disclosed or claimed.

FIGS. 10A and 10B show oblique views of embodiments of an elastomericcontact insert of an elastomeric contact that may be used with aconductivity measurement component in any of the embodiments disclosedor claimed.

FIGS. 11A and 11B show oblique views of additional embodiments of anelastomeric contact insert of an elastomeric contact that may be usedwith a conductivity measurement component in any of the embodimentsdisclosed or claimed.

FIGS. 12A-12C show cross-sectional views of embodiments of anelastomeric contact insert of an elastomeric contact that may be usedwith a conductivity measurement component in any of the embodimentsdisclosed or claimed.

FIGS. 13A-13D show various views of embodiments of a housing thatsupports an elastomeric contact insert in an elastomeric contact thatmay be used with a conductivity measurement component in any of theembodiments disclosed or claimed.

FIG. 14 shows a schematic view of various components forming a4-terminal sensing circuit in a fluid conductivity cell that may be usedin any of the embodiments disclosed or claimed.

FIGS. 15A and 15B show cross-sectional views of additional embodimentsof a housing that supports an elastomeric contact insert in anelastomeric contact that may be used with a conductivity measurementcomponent in any of the embodiments disclosed or claimed.

FIG. 16 illustrates a view of a fluid circuit according to embodimentsof the disclosed subject matter.

FIG. 17 illustrates a closeup view of a portion of FIG. 16.

FIG. 18 illustrates a closeup view of another portion of FIG. 16.

FIG. 19 illustrates a junction of a common flow channel and aconcentrate channel according to embodiments of the disclosed subjectmatter.

FIG. 20 illustrates a junction of a common flow channel and aconcentrate channel according to embodiments of the disclosed subjectmatter.

FIG. 21 illustrates a junction of a common flow channel and aconcentrate channel according to embodiments of the disclosed subjectmatter.

FIG. 22 illustrates a junction of a common flow channel and aconcentrate channel according to embodiments of the disclosed subjectmatter.

FIG. 23 illustrates a water purification system according to embodimentsof the disclosed subject matter.

FIG. 24 illustrates a medical treatment system according to embodimentsof the disclosed subject matter.

FIG. 25 illustrates a waste water line according to embodiments of thedisclosed subject matter.

FIG. 26 illustrates another waste water line according to embodiments ofthe disclosed subject matter.

FIG. 27 illustrates another waste water line according to embodiments ofthe disclosed subject matter.

FIG. 28 illustrates a medicament admixing system according toembodiments of the disclosed subject matter.

FIG. 29 illustrates another medicament admixing system according toembodiments of the disclosed subject matter.

FIG. 30 illustrates another waste water line according to embodiments ofthe disclosed subject matter.

FIG. 31 illustrates a view of an opening of a housing of a conductivitysensor according to embodiments of the disclosed subject matter.

FIG. 32 illustrates an axial section of the embodiment of FIG. 31 takenalong plane II-II.

FIG. 33 illustrates a view of an exemplary housing according toembodiments of the disclosed subject matter.

FIGS. 34 through 36 illustrate views of housings with rectangular,elliptical, and triangular openings according to embodiments of thedisclosed subject matter.

FIGS. 37A and 37B illustrate a portion of an axial section through theplane indicated by VII-VII of FIG. 31.

FIG. 38A illustrates a portion of a cross-section view of a spaceraccording to another embodiment of the disclosure.

FIG. 38B illustrates a portion of a cross-section view of a spaceraccording to another embodiment of the disclosure with an insertedelectrode.

FIGS. 39, 40A, and 40B show alternative embodiments in which, ratherthan using standoffs extending from the aperture to focus the forces foraligning and engaging the electrode, the electrode itself is shaped toprovide a similar effect by forming a non-round electrode that engagesthe walls of the aperture at predefined points.

FIGS. 41A and 41B show an electrode embodiment in which the entirecircumference engages the outer aperture and is shaped as an annularbarb and the electrode may have a recess with an inner aperture pressingagainst the base of the recess to form a seal while the electrode ispressed into engagement with the inner aperture wall.

DETAILED DESCRIPTION

FIG. 1A shows an interface element 135 having contacts 137A and 137Bwhich are positioned to engage an electrode 146, or other conductiveelement, at two points thereon. The electrode 146 is supported by amember 136 which has an opening 143 covered and sealed by the electrode146. The member 136 may be a portion of a wall of a conductivitymeasurement device such as described with reference to FIGS. 7A-7E. Theinterface element 135 and member 136 are moved toward each other so thatthe contacts 137A and 137B are moved toward the electrode 146 as shownby the arrows. FIG. 1B shows the interface element 135 and member 136have stopped moving due to interference engagement with contact 137A.This leaves contact 137B spaced apart from the electrode 146. This isdue to the angles position of the electrode 146 relative to the contacts137A and 137B. The angled position of the electrode 146 circumstance isexaggerated in the figures and the contact failure may not be as clearcut in a real-world circumstance due variability due to imperfectmanufacturing of the member 136 and electrode 146.

FIGS. 1C and 1D show how the interposition of a compliant multiconductorelement 140 may allow complete contact between the electrode and both ofthe contacts 137A and 137B. Referring briefly to FIG. 1E the compliantmulticonductor element 140 has an elastomeric block 142, which may haveadditional features cut out of it to make it more compliant as discussedbelow. Flexible conductors 141 (only one of many parallel conductors isindicated by the reference numeral) are attached on opposite faces 145Aand 145B of the elastomeric block 142 which, as illustrated, areperpendicular to the plane of the drawing page, of the elastomeric block142. The flexible conductors 141 may be thin wires or metallic tape orconductive traces deposited on the elastomeric block 142. The flexibleconductors 141 wrap around the opposing faces 145A and 145B and bridgeacross (in the direction parallel to the plane of the drawing page) sothat when interposed between interface element 135 and the member 136,this creates an electrical continuity between a region 138A of theelectrode 146 and contact 137A and between region 138B of the electrode146 and contact 137A. The electrical continuity contact may be formed bymultiple conductors 141. It can be observed that the compliantmulticonductor element 140 deformation when the interface element 135and the member 136 are forced together allows continuity to be madebetween the electrode 146 and the contacts 137A and 137B. The scales ofthe elements shown are not necessarily representative of a real-worldembodiment and the sizes and numbers of elements are modified to fordescription purposes.

The compliant multiconductor element 140 may conform to the so-calledZebra elastomeric connector used commonly for making one-to-oneelectrical contact between a row of contacts of a liquid crystal displaypanel and corresponding contacts pads of a graphics processing unit.Note that instead of conductors 141, the compliant multiconductorelement 140 may be a many-layered sandwich of conductive and insulatingmaterials. The conductive layers may be, for example, carbon-filledelastomeric material. In typical applications, known elastomericconnectors are used for extremely high pitch contact spacingapplications in which the contact size and spacing is no more than amillimeter or two and commonly a minor fraction of a millimeter. Thepresent system may employ contacts that are several millimeters wide.Another difference from conventional uses of Zebra connectors is thenumber of contacts. Zebra connectors are generally used to map manycontact pads, in the tens, hundreds, or thousands rather than two as inthe present embodiments. Yet another difference is that the multiplecontacts, for example, 137A and 137B are electrically connected by thecompliant multiconductor element 140 to a single electrode 146 atmultiple positions, rather than respective contacts. Still anotherdifference is that the disclosed compliant multiconductor element 140has an aspect ratio of about unity so that it can maximally fill thearea of a round electrode. As discussed below, the compliantmulticonductor element 140 may be captured and held to the electrode bya housing to form a part of a consumable component of a medicaltreatment device. Other differences in the application will be revealedin the following embodiments.

FIG. 2 shows an overview of an online water purification, proportioningmedicament generation, and treatment system 100, according toembodiments of the disclosed subject matter. A water purification module102 receives tap water 108 from a municipal water supply. The waterpurification module 102 purifies the water and checks its purity, undercontrol of a controller 112 and using a water quality sensor (219 inFIG. 2). The water quality sensor 219, in embodiments, includes aconductivity sensor. The water purification module 102 utilizes one ormore filter modules 130 which are replaced at intervals to help maintainthe ability to generate product water that is sterile and ultra-pure.Product water 109 from the water purification module 102 is conveyed toa medicament proportioning module 104 which mixes one or moreconcentrates and the product water 109 in a replaceable fluid circuit132 to generate a medicament 111. The medicament concentrates arediluted in a predefined proportion to generate product medicament 111.One or more concentrates may be utilized and combined in the productmedicament 111. The water purification and medicament generation areperformed in in-line fashion and on-demand, which means water ispurified and mixed with medicament concentrate as a continuous process,at a rate of consumption and as demanded by a final consumer, in thiscase, a cycler 106. Waste produced by the medicament proportioningmodule 104 is conveyed as indicated at 115 to a drain 117. Waste 110,for example spent medicament, is conveyed to the same or other drain117.

Each of the water purification module 102, the medicament proportioningmodule 104, and the cycler 106 may include a respective controller 112,114, and 116. All of the controllers 112, 114, and 116 may be incommunication as indicated by lines 122 and 124. In alternativeembodiments, a smaller or larger number of controllers may be used andthey may be associated with each module 102, 104, and cycler 106 orshared among the modules 102, 104, and cycler 106. One or more userinterfaces, figuratively indicated at 101 and 103, may be connected toone, two, or the entire water purification module 102, medicamentproportioning module 104, and/or cycler 106. Connections between theuser interfaces 101, 103, indicated at 123 and 125, may be wired orwireless. In embodiments, control may be provided through a single userinterface 103, and each module may transmit commands responsive tocommands from the user interface 103 to the respective controllers 112and 114 of the water purification and medicament proportioning modules102 and 104, in parallel or serially. In embodiments, the cycler 106receives and returns blood in arterial and venous lines 120A and 120B,respectively. In other embodiments, medicament is conveyed to and from apatient, for example in a peritoneal dialysis treatment.

FIG. 3 shows details of the water purification module 102 of theembodiment of FIG. 2. Referring now to FIG. 3, a water purificationmodule 102 receives tap water from an inlet 214, the tap water beingpumped by a pump 212 and passed through a sediment filter 202, a waterquality sensor station 219, and an activated carbon filter 204. Waterfrom the activated carbon filter 204 is received by a two-stagedeionization filtration element 244 that includes a primary resin cationstage 205, a primary resin anion stage 206, and a secondary mixed resinbed 208. The primary resin cation stage 205 and the primary resin anionstage 206 may be combined in a single replaceable unit 242 or may beseparately replaceable. The primary resin cation stage 205, the primaryresin anion stage 206, and the secondary mixed resin bed 208 may also becombined in a single replaceable unit in alternative embodiments.Deionized water from the two-stage deionization filtration element 244passes through a diverter valve 230 which is controlled by a controller240. The diverter valve 230 may selectively direct a flow of deionizedwater to a drain outlet 232. Deionized water passing through thediverter valve 230 for the generation of product water is directed to aheater 220, a degassing filter 222, and two or more sterile filtersconnected in series to form sterile filter stage 210 from which productwater may be drawn through a product water outlet 216. A vacuum pump(not shown) may be provided on an air side of the degassing filter 222.The degassing filter 222 may have a hydrophobic membrane to allow gas tobe removed from water flowing through it. The water purification module102 may contain a replaceable unit 113 that includes a conductivitysensor according to any of the disclosed embodiments for detectinginitial water quality.

The water quality sensor station 219 may output a signal indicatingwater quality, for example, a signal indicating conductivity of thewater, which may be numerically cumulated by the controller 112 togenerate, for any point in time, a remaining life of any of the filtersprovided herein. The water quality sensor station 219 may include aparticle counter, a conductivity sensor, an optical opacity sensor, a pHsensor, a lab-on-a-chip chemical assay sensor, and/or another type ofwater quality sensor. The user interface 101 and/or 102 may allow theentry of other data regarding water quality. For example, a worst-caseupper bound, or data related thereto, of raw water constituents may beprovided. An algorithm that predicts the rate of the various components,based on a measured indicator, may then be used to predict the rate ofall contaminant constituents. In an example embodiment, the algorithmmay predict that all contaminants are in the same proportion as apredefined value such that an indication of conductivity by the waterquality sensor station 219 may thereby indicate the concentrations ofthe various contaminants. In embodiments, the controller 112 may outputan indication of the remaining life of the various components or anindication that a component is at or near expiration. In a particularembodiment, the useful life of the deionization resin beds may beestimated based on conductivity indicated by water quality sensorstation 219. The estimation of the remaining life may be based on thedata carried by the data carrier of the replaceable tagged componentindicating characteristics such as the capacity or type ofdecontaminating media employed thereby. The water quality sensor station219 may be positioned at any suitable point downstream of the inlet 214,even though shown downstream of the sediment filter 202.

The pump 212 and sediment filter 202 may form permanent orinfrequently-replaced components that are ordinarily not replaced by theuser. The entire water purification module 102 is adapted for use by ahome-bound patient and/or a helper although its features of compact sizeand low water volume requirement make it attractive for use in criticalcare environments. The tap water inlet 214 may be fitted with an adaptersuitable for connection to an accessible permanent or temporaryconnection so that, for example in critical care environments, the waterpurification module 102 may be wheeled to a point of use and connectedto a nearby water tap with such a connection fitting. In embodiments,the water purification module 102 is combined with the medicamentproportioning module 104 in a single housing so that it can be wheeledto a point of use and/or compactly housed for use in a home.

Each of the replaceable components (activated carbon filter 204, primaryresin cation stage 205, primary resin anion stage 206, replaceable unit242, or sterile filter stage 210) may be fitted with a respective datacarrier 201, 203, 209, 207, 211 such as a bar-code or radio-frequencyidentification (RFID) tag that carries a unique identifier respective tothe attached component (again, attached component may be any of theactivated carbon filter 204, primary resin cation stage 205, primaryresin anion stage 206, replaceable unit 242, or sterile filter stage 210and will generally be referred to as replaceable tagged component).Product water may be drawn through the product water outlet 216.

A reader 245 may be attached to the purification module 102 and may bepositioned so as to actively or passively read the data carrier 201,203, 209, 207, 211 of the replaceable tagged component. Reader 245 maybe a scanner for an RFID, a bar-code scanner, a smart-chip reader, orany other type of data carrier reader, and may connect optically,electromagnetically, electrically through conductive contacts, or by anyother suitable means. The information stored on data carriers may allowthe controller 240 to verify that the correct type of replaceable taggedcomponent is installed. The controller 240 may detect the removal ordisconnection of a replaceable tagged component as well. In anembodiment, the controller 240 may generate a refuse signal and takecorrective action (such as preventing use of the water purificationmodule 102 or blocking installation of the replaceable tagged componentor some other action).

FIG. 4 shows an overview of an online water purification, proportioningmedicament generation, and treatment system 351. The water purificationmodule 102 and medicament proportioning module 104 form a medicamentgeneration system 355 and are commonly housed in a housing 350 with auser interface 101. The cycler 356 (or generally, a medical treatmentdevice that consumes medicament generated by the medicament generationsystem 355) may form a separately housed device that is signally andfluid connected to the medicament generation system 355. Communicationsmodule 358 interconnects the controllers 304 and 116 of the medicamentgeneration system 355 and cycler 356 respectively.

By combining the medicament generation system 355 with a cycler, asystem suitable for use in a home, critical care, or clinic may beprovided without a need for specialized services such as high capacitymunicipal water supply, power, or drainage. For example, high volumewater supply is typically required in reverse osmosis-based waterpurification system. In the present embodiments, municipal water 360 isdeionized using consumable deionization filter beds, allowing normalrates of water flow and drainage 317 in a services supply 362 that istypical of a home or the room services of a hospital. With powerrequirements at residential or typical hospital-room voltages andcurrents, available services allow the proportioning medicamentgeneration, and treatment system 351 to be used for home and criticalcare, as well as in clinics. For clinics, the rapid set-up of a newinstallation can be facilitated as well because expensive capitalinfrastructure of an online medicament generation system can be avoided.

As in the embodiment of FIG. 2, the water purification module 102receives tap water 108 from a municipal water supply. The waterpurification module 102 purifies the water and checks its purity undercontrol of controller 304. The water purification module 102 utilizesone or more filter modules 130 which are replaced to help maintain itsability to generate product water that is sterile and ultra-pure.Product water 109 from the water purification module 102 is conveyed toa medicament proportioning module 104 which mixes concentrates providedin a replaceable fluid circuit 132 in a predefined proportion togenerate a medicament 311. The water purification and medicamentgeneration are performed in on-line fashion and on-demand, which meanswater is purified and mixed with medicament concentrate as a continuousprocess, at a rate of consumption and as demanded by a final consumer,in this case, a cycler 356. Waste produced by the medicamentproportioning module 104 is conveyed as indicated at 115 to a drain 317.Waste 110, for example spent medicament, is conveyed to the same drainor another drain 317. The cycler 356 may be of any type includinghemodialysis and peritoneal dialysis as well as other types of treatmentsystems.

The communication module may allow the controller 116 to send specificcommand signals to the medicament generation system 355, for example, tostart and stop medicament generation. In a system in which the cycler356 is not adapted to send specific commands, a status vector can betranslated by the communications module 358 to convert it to one or moresuitable commands. A status vector may include information such aswhether a blood pump of the cycler 356 is running.

Controller 364 and 366 may communicate, respectively, with themedicament generation system 355 and cycler 356. The controllers 304 and116 may generate operation or treatment logs and/or maintenanceinformation which they may send the controller 366 for furtherdistillation, synthesis, storage, or communication to other facilitiesand/or remote professional care management or maintenance personnel.

FIG. 5 shows details of an embodiment of medicament proportioning module104 shown in FIG. 2. A sealed fluid circuit 401 is partially supportedby a cartridge support 406. Flow lines supported by the cartridgesupport 406, shown generally at 408 may be tubes attached to thecartridge support 406 or formed therein by molded and sealed channels orin attached seam-welded flexible panels or by other suitable means. Thesealed fluid circuit 401 may also include all the other lines and fluidcircuit elements illustrated including such as waste line 422, inletline 431, medicament concentrate lines 433, product medicament line 435,control valve 420, junction 437, and inlet sterile filter 445 to form asingle pre-connected sterile disposable unit along with the flow lines408 (and other elements supported by the cartridge support 406 describedbelow). As explained, the entire sealed fluid circuit 401 shown in FIG.5, save for the inlet line 431 inlet and product medicament line 435 arepre-connected and sealed from the external environment. The sealed fluidcircuit 401 may be sterilized as a unit, for example, gamma-sterilizedor heat-sterilized.

A source of pure water can be connected by way of a connector 414 whichis capped and sterile-sealed prior to connection. By sterile-sealed itis meant that a seal is formed sufficient to physically block anycontaminants from entering. A resistivity sensor 107 of the form of anyof the disclosed conductivity sensor embodiments may be provided in thewater inlet line. A sterile filter 445 ensures that any contamination inthe flow, for example, resulting from touch contamination or acontaminated connector on the pure water source, is trapped by thesterile filter 445. Thus, sterile filter 445 forms part of the completesterile barrier such that the entire sealed fluid circuit 401 has acontinuous sterile barrier even after the connector 414 is unsealed, atleast while the product medicament line 435 connector is capped with cap421. The sterile filter may be one with a 0.2 μm membrane to blockbacterial contaminants. Note that by ensuring that completely steriledeionized water flows into inlet line 431 and because the entire sealedfluid circuit 401 is sealed and sterile, the unit once set up and readyfor treatment can be filled and used over an extended treatment withoutthe risk of proliferation of contaminants. For example, the sealed fluidcircuit 401 can be prepared for use and primed and used, up to 24 hourslater. Alternatively, it may be used for more than one treatment.

Pure water flows through the sterile filter 445 at a rate of pumpingdetermined by the pump 442. To match the rate of production of purifiedwater with the rate of pumping by pump 442, the source of purified watermay generate a constant supply into an accumulator, it may pumpcontinuously with overflow to a drain, or a pump of the waterpurification module 102 may be commanded in response to the controller402 of the medicament proportioning module 104. Reference numeral 432indicates that a single concentrate, such as lactate buffered dialysate,can be substituted for the multiple-component concentrate. This is trueof any of the embodiments.

The cartridge support 406 may be received in a medicament proportioningmodule 104 which may further be a stand-alone unit or combined with awater purification module 102. As illustrated, the medicamentproportioning module 104 is a stand-alone unit. Purified water isreceived at an inlet 431, which forms a part of a disposable sterilefluid circuit that includes all the fluid lines and circuit componentsillustrated in the figure and/or discussed herein. Pump 442 pumps waterthat flows at a rate controlled by a controller 402. Pumps 444 and 446regulate flows of respective medicaments concentrates in medicamentconcentrate lines 433 so that they are diluted in a precisely controlledratio by the flow of water pumped by the pump 442. A first concentratein container 428 pumped by pump 444 is combined in junction 437 with theflow of water pumped by pump 442, thereafter flowing into a conductivitymeasurement module 415 which generates a signal indicative of theconcentration of medicament concentrate in the mixture emerging from thejunction 437. A temperature signal indicating a temperature of the sameflow is also generated by a temperature transducer 413. The signalsindicating conductivity and temperature are applied to the controller402 which converts them to concentration responsively to stored (in adata store of the controller—not shown separately)conductivity-temperature curves for the solution of the diluted firstconcentrate stored in the container 428. A secondary set of conductivitymeasurement modules 416, 417, 418 and temperature transducers 412, 411,410 may be provided to provide signals indicating conductivity andtemperature of the same flow as a confirmation. If the calculatedconcentrations differ, the controller 402 may generate a signalindicating a corresponding error condition. In response, the controller402 may generate an error indication on a user interface 405 or halt theflow of medicament, or divert it through a diverting valve 420 to awaste line 422, for example.

The conductivity measurement modules 415, 416, 417, and 418 may eachhave a pair of electrodes sealed to a housing as described in moredetail according to specific embodiments. Each electrode may be asdescribed with reference to electrode 146 with a portion of a housingdefining a fluid channel of each conductivity measurement module 415,416, 417, and 418 corresponding to member 136. The interface element 135corresponds to a permanent fixture, having the interface element andcontacts 137A, and further having excitation and voltage detectioncircuits connected to the contacts 137A, the latter not being shownseparately in the schematic of FIG. 5.

The second medicament concentrate is pumped by pump 446 from container430 into a junction so that the second concentrate is mixed with thediluted first concentrate. The diluted and mixed first and secondconcentrates flow into a conductivity measurement module 417 whichgenerates a signal indicative of the concentration of medicamentconcentrate in the mixture emerging from the junction. A temperaturesignal indicating a temperature of the same flow is also generated by atemperature transducer 411. The signals indicating conductivity andtemperature are applied to the controller 402 which may convert them toconcentration or some other parameter or the values may be used directlyfor comparison to a reference value. The temperature may be used tocompensate the conductivity by a scaling factor to adjust for adifference between reference conductivity value taken at one temperatureand an actual temperature at which the fluid conductivity is measured.In the present disclosure, in embodiments where concentration is anidentified output from conductivity measurement it should be understoodthat temperature compensated conductivity or a raw signal may be used aswell in any embodiment. As indicated, the conductivity measurements aremade by the conductivity measurement modules 415, 416, 417, and 418.Note that a conductivity module of the same description may also be usedfor water quality sensing as described with reference to referencenumeral 219.

A secondary (or redundant) set of conductivity measurement module andtemperature transducers may be provided to provide signals indicatingconductivity and temperature of the same flow as a confirmation. If thecalculated concentrations differ, the controller 402 may generate asignal indicating a corresponding error condition. A final medicamentproduct concentration flows through the line indicated at 408 into anaccumulator 404 which has an expandable volume whose pressure may besubstantially determined by a spring constant due to a spring-basedrestoring force. A pressure sensor 127 may measure the pressure in theaccumulator 404. A connected device, such as cycler 106 can drawmedicament through line 435. A cap 421 at the connector ensures asterile output line and is removed before connection.

Referring now to FIG. 6, an embodiment of a fluid circuit cartridge 500is illustrated such as the fluid circuits of the medicamentproportioning module 104 of any of the foregoing embodiments. Thecartridge has a generally planar support 529 for the various fluidcircuit elements. In embodiments, a fluid circuit is embodied in by afluid circuit pattern defined in the support 529, for example by moldedchannels or seam welding or a combination thereof. Alternatively, thefluid circuit may be made up of discrete channel elements such as tubes,junctions, and valves. A fluid circuit 533 supported by the support 529has channel elements 503 (indicated at 503 but also appearing at variouslocations as indicated), temperature measurement cells 504, 507, 508,511, concentration measurement modules 535A, 535B, 535C, and 535D,pumping tube segments 526, 527, 528, an accumulator 502, and pinch valvetube segments 522, 523, junctions 501, 509. Cutouts 513 in the support529 allow pumping actuators 532, 531, 530, to mechanically accesspumping tube segments 526, 527, 528, respectively, and valve actuators536, 537, to access pinch valve tube segments 522, 523, in order to pumpfluid or halt or allow the flow of fluid.

Pure water enters in line 541 from a water purification module 102pumped by pumping actuator 532 through pumping tube segment 526. Aninline sterile filter 515 ensures that any touch contamination, or anycontamination, does not enter the cartridge fluid circuit. Pumping tubesegment 526 (as well as segments 527 and 528) may be made of aspecialized construction and material that provide low material creepand precise size to allow consistent and predictable rates to beprovided through the regulation of the pumping actuator 532. The rate ofrotation of the pumping actuator 532 is regulated by a controller (notshown) to provide a medicament product flow required by a downstreamtreatment such as a flow commanded by a cycler 106 and received thereby,or some other consuming device such as storage container.

A first concentrate is received through a first medicament concentrateline 542 and is pumped at a rate controlled by the controller to providea predefined dilution rate of the combined flow emerging from thejunction 501. The mixed diluted first concentrate flows into a firstconcentration measurement module 535A. Each concentration measurementmodule 535A-535D is described in more detail with reference to FIGS. 7Athrough 7E, infra. The mixed diluted first concentrate flows into thefirst concentration measurement module 535A and contacts conductiveelectrodes, one of which is indicated at 512. A current is driventhrough a column channel of the concentration measurement module 535 aand a voltage drop is measured across the conductive electrodes 512using the conventional four-point conductivity measurement scheme inorder to reduce contact resistance error. The fluid emerging from thecolumn channel is received in a temperature measurement cell 511 andthen flows into a second concentration measurement module 535B withtemperature measurement cell 508 and conductive electrodes 510 (only oneindicated, but the other is evident by inspection). The secondconcentration measurement module 535B provides a redundant indication ofconductivity and temperature to confirm accuracy by agreement betweenconcentration measurement module 535A and concentration measurementmodule 535B. The controller or an independent module may output a signalor data indicative of concentration based on temperature andconductivity. The signals indicating conductivity and temperature may beconverted to concentration responsively to stored (in a data store ofthe controller—not shown separately) conductivity-temperature curves forthe solution received thereby. The same is done using temperature andconductivity signals from concentration measurement module 535C andconcentration measurement module 535D as well.

The diluted first concentrate is received at a junction 509 where itcombines with a flow of second concentrate pumped through the pumpingtube segment 528 by pumping actuator 530. The second concentrate isdrawn through a second medicament concentrate line 543. The flow rate ofthe diluted first medicament is determined by the combined flow rates ofthe flows in pumping tube segments 526 and 527 which are regulated bythe controller (not shown) through control of the actuator (532, 531)speeds. In a similar manner, the flow through the pump segment 528 isregulated by the rate of the pumping actuator 530 such that theconcentration of the mixture emerging from the junction 509, whichincludes the first and second concentrates plus the dilution water, isregulated by the relative rotation rates of the three pumping actuators532, 531, and 530. In this example, the concentration of the mixtureemerging from the junction 509 represents a final concentration ofproduct medicament and it is measured using the concentrationmeasurement module 535C and then redundantly measured using theconcentration measurement module 535D. As described above, theconcentration measurement module 535C and the concentration measurementmodule 535D have conductive electrodes 506 and 505, respectively andtemperature measurement cells 507 and 504. The conductive electrodes512, 510, 506, 505 (each of the numerals identifying a pair ofconductive electrodes) make contact with fluid in a respective one ofthe conductivity measurement columns 516, 517, 518, 520 (shown in brokenlines indicating they are behind the fluid circuit 533 support 529).

The product medicament flows into a diaphragm chamber of an accumulator502 which reduces flow fluctuations by expanding and contracting withthe help of an urging element. Flow enters the accumulator 502 at ajunction 525 and flows out through a pair of pinch valve tube segments522 and 523, each leading to a respective outlet line 544 and 545. Theoutlet line 544 is connected to a drain and the outlet line 545 isprovided with a connector for connection to a consuming device such ascycler 106. The cartridge 500 may be pre-connected with concentratecontainers 492 and 493, capped with caps 495 so that the entire assemblyis sealed from the environment, and sterilized before packaging fordelivery and/or storage. The cartridge 500 may be attached to acontainer 494, which can be rigid, such a box such that it can beremoved from the container 494 and slid onto a shelf while positioningthe cartridge 500 in the medicament proportioning module 104, where thefirst medicament concentrate line 542 and second medicament concentrateline 543 are of sufficient length to allow them to extend between thepositioned cartridge 500 and a storage for the container 494. Inembodiments, the container 494 can be a cardboard box or plastic box.

Referring to FIGS. 7A through 7D, a concentration measurement module 535as described above is now detailed according to an example embodiment. Asection of a cartridge support 556 may correspond to a portion ofcartridge 406, or the support 529 of cartridge 500 described above.Thus, the edges of the cartridge support 556 may be considered to extendand not be limited to the particular shape or size illustrated, theportion shown being merely a portion of a larger support structure. Aninlet flow of conductive fluid enters through an inlet channel 566molded into the cartridge support 556. A wall 567 rises from the planeof cartridge support 556 to define the channel 566. The edge of the wall567 may be sealed with a plastic film to make channel 566pressure-tight. Flow, indicated by arrow 564, entering the channelinternal volume 557 from other parts of the cartridge support 556 leavesthe channel 566 through an opening 568 where it flows into a flow columnhousing 575 as indicated by arrows 574, and flows from an end oppositethe entry to an opening 570 in cartridge support 556, through atemperature sensing region 558. From there, the flow traverses atemperature measurement chamber 563 toward an exit channel 572 which ison an opposite side from the opening 570 where the flow entered thetemperature measurement chamber 563. The flow leaves the concentrationmeasurement module 535 as indicated by arrow 562. The temperaturemeasurement chamber 563 and the exit channel 572 may be sealed in thesame fashion as channel 566 such that the temperature measurementchamber 563 forms a flat broad chamber. A temperature transducer may beplaced against the face of the film that is used to close thetemperature measurement chamber 563 providing a broad contact area foraccurate temperature measurement that limits edge losses that can biasthe temperature measurement. In addition, a zero-flux temperature sensorcan be used which actively cancels heat flux due to conduction throughthe major face of the temperature measurement chamber 563, providing anexcellent application here because of the high sensitivity ofconcentration to temperature. Bosses 552 may be provided for support andadditional structure and sealing competence in the cartridge support556.

Conductive electrodes 550 may be bonded, welded, press-fitted, molded orotherwise affixed to the cartridge support 556 (a portion being shown at576). In one embodiment, in use, spring biased contacts 571 and 573 maybe pressed into each conductive electrode 550 while at the same time, atemperature transducer 577 is held against the temperature measurementchamber 563 as a sensor backplane 587 portion is held against theconcentration measurement module 535 as a result of the entire cartridgebeing positioned in place in medicament proportioning module 104 andengaged for use. That is, when a cartridge of any of the embodiments,carrying the concentration measurement module 535 is positioned in placein a medicament proportioning module 104 and registered, the springbiased contacts 571 and 573 and temperature transducer 577 are placedagainst the conductive electrodes 550 and temperature measurementchamber 563 so that measurements can be taken by the connectedcontroller. Note that FIGS. 7B and 7D are exploded views. Alternatively,elastomeric contacts may be used in place of spring biased contacts 571and 573 as will be described in detail below.

Referring to FIG. 7E, a concentration measurement module 535′ similar toconcentration measurement module 535 in all respects except that acompliant multiconductor device 583 is used to connect contact pads 571′and 573′ to the conductive electrodes 550 shown by hidden lines. Thecompliant multiconductor device 583 has an elastomeric contact insert754 partially enclosed by a housing 752. Further details are describedinfra. The elastomeric contact insert 754 connects contact pads 571′ and573′ to respective points on the conductive electrodes 550. Thisreplaces the contacts the spring biased contacts 571 and performs thesame function with greater reliability and tolerance of manufacturingvariability.

Note in any of the embodiments described herein, other types of tubingclosures may be used. For example, frangible-seal valve-type closuresmay be used. An example of a frangible-seal valve is described in U.S.Pat. No. 4,586,928. The medicament proportioning module 104 may beequipped with an actuator to open a frangible-seal valve automaticallyduring a set-up procedure. In a method, after installing the fluidcartridge, a linear actuator aligned with a frangible-seal valve by thepositioning of the cartridge, may be controlled to open the valve inresponse to a command from a controller. The command may follow thecomplete preparation for a treatment, for example and a user input to auser interface indicating that the system should begin priming inpreparation for treatment.

Note in any of the embodiments, a single sterilizing filter may be usedto fill the concentrate containers of multiple fluid circuits. This maybe done by connecting multiple fluid circuits to a single filter with amanifold. The latter may be sterilized prior to use. The fluid circuitsconnected to the filter and manifold may be sterilized after connectionto prevent touch contamination from making the connection or theconnection may be done in a sterile environment. The circuits may befilled and then sealed.

FIG. 8A shows a portion of a fluid circuit cartridge 800 to illustratehow electrical, thermal, and mechanical engagement of actuators andsensors are provided using the fluid circuit cartridge device. A fluidcircuit base planar element 812, for example, injection molded plastichas molded walls that define channels 826 having a generally uniformcross section and may be covered by film by welding or adhesive. Thewall extends from a base portion of the planar element forming a troughand the edges of the walls remote from the base element are then sealedwith the film, fully closing the trough to form the channel. The filmmay be thin to minimize thermal resistance between a temperature sensor815 (supported on a support 814) and the fluid carried by the channel826. A channel 826 portion for engagement with temperature sensor 815may be flattened out to reduce edge flux effects on the temperaturemeasurement. In general, the channels 826 may be straight or curvedsegments that convey fluid with minimal resistance. Openings such asindicated at 804 allow the flow in the channels 826 to flow (see arrows813) into other features such as a column channel 802 for measuringconductivity using electrodes 808 and the accumulator (not shown).

In one embodiment, the electrodes make electrical contact with contactpins 806 (which may be four in number for measuring contact resistanceand for four-point measurement to minimize the effect of contactresistance on the conductance signal) also supported on an opposingplanar actuator support indicated by dot-dash line along support 814 butwhich may be any type of support or supports. The temperature sensor 815and contact pins 806 may be backed by urging elements such as springs.

In an alternative embodiment, instead of contact pins 806, theelectrodes make electrical contact with elastomeric elements (which mayalso be four in number for measuring contact resistance and forfour-point measurement to minimize the effect of contact resistance onthe conductance signal) as will be described in detail below.

Pumping tube segments 820 can be clamped between a roller actuator 822and a race 824, respectively supported on support 814 and an opposingsupport 829. A pinch clamp tube segment 832 of tubing can be positionedbetween clamping elements 830 supported on support 814 and clamped by apinch clamp tubing segment. All of the engagements required areconveniently provided by moving the supports 814 and 829 in opposingdirections as indicated by arrows 816 around the fluid circuit baseplanar element 812. Further, some of the fluid carrying features areformed by the fluid circuit base planar element 812 including thechannels. Connections to the tube segments can be formed in the channelby molding as well. A tubing segment with a valve 845 such as afrangible-seal valve may be positioned to be opened at a time of set upand priming by an actuator motor 843 and actuator 844. Here the fluidcircuit base planar element 812 may serve as a backstop to resist theforce applied to the valve 845 or the actuator 844 may provide aclamping or scissor action that does not require an opposing support.

Another fluid circuit feature that can be formed in the fluid circuitbase planar element 812 is a pressure sensor region 847, which may beformed similarly to the temperature channels 826. The overlying filmprovides a compliant surface that can apply force to a strain gauge 848pressed into engagement with the overlying film of the pressure sensorregion 847 when the 816 are positioned to engage the fluid circuitcartridge 800 elements. Openings 804 and elbows 849 may also be made inthe fluid circuit base planar element 812 with to flow fluid fromchannels 826 to tubular portions such as a pinch clamp tubing segment832, a valve 845, or pumping tube segment 820 attached at the oppositeside of the fluid circuit base planar element 812.

As discussed above, the fluid circuit base planar element 812 may alsosupport a data carrier 833 that is positioned when the cartridge isinstalled, to be read by a reader 831.

In embodiments, the fluid circuit base planar element 812 may be moldedsuch that all the side action mold parts can be drawn in the samedirection. In embodiments, the fluid circuit cartridge 800 may positionall the sensor and actuator surfaces on one side of the fluid circuitbase planar element 812. This allows all the actuators and sensors andtheir associated wiring and circuitry to be positioned on a first sideand supported by only the support 814. The opposing support 829 can bepassive. In the example shown, the opposing support 829 supports onlythe race 824 (a member often called a “shoe”). To facilitate tightpacking of the elements, some of the larger elements such as columnchannel 802, pinch clamp tubing segment 832, a valve 845, and pumpingtube segment 820 can be attached on the opposite side. This allows thesensors and actuators to be larger than they would be able to be ifthese elements were on the other side. Rather, most of the first side isflat or open. This can allow the cartridge to be much smaller thanotherwise possible.

FIG. 8B shows a portion of a fluid circuit cartridge 801 similar to thatof FIG. 8A except that instead of contact pins 806, the electrodes makecontact with current source and voltage measurement contacts using theelements shown in FIG. 8C. FIG. 8C shows a contact device 854 accordingto embodiments of the disclosed subject matter. A portion of the fluidcircuit base planar element 812 defines a wall of the column channel802. The electrode 808 seals the flow space enclosing the fluid whoseconductivity is to be measured. A housing 752 holds an elastomericcontact insert 754 against the electrode 808. Elastomeric contact insert754 is shown by hidden lines at 863. The housing is attached to thefluid circuit base planar element 812 or the electrode itself by anysuitable means including an interference fit, adhesive attachment,fasteners, or other means. A contact element 851 has a substrate 853with current source 860 and voltage measurement 861 contacts. When acartridge of which fluid circuit base planar element 812 is a part ismoved relative to the other means the contact element 851, theelastomeric contact insert 754 is squeezed between the electrode 808 andthe current source 860 and voltage measurement 861 contacts. See FIGS.13A through 13D for more. The configuration avoids the need for contactpins 806. Other benefits of the elastomeric contact insert 754 andequivalents apply. Thus, the electrode 808 and other means the contactelement 851 can

Referring now to FIG. 9A, as in the fluid circuit 533, conductivity maybe measured using series concentration measurement modules that areconnected in series or series/parallel as described with reference toFIG. 5. In the present embodiment, which may be substituted into any ofthe foregoing or following embodiments, conductivity is measured basedon multiple paths as well as the fluid column in a respectivemeasurement column, such as columns 702. A fluid flows through columns702 which are joined by channel elements 703. Additional channelelements may be included such as to inject concentrates or diluents asdescribed with reference to FIG. 6. In the latter embodiment, theresistance of fluid to the flow of current was obtained betweenconductive electrodes at either end of a respective measurement column.In embodiments, additional measurements using the same conductiveelectrodes may be made. In FIG. 9A, conductive electrodes 701 arelabeled A through H. Contact resistance on the dry side of eachelectrode may be made between current contacts and voltage sensecontacts which are provided and used according to the well-knownfour-point resistance measurement technique. In the present embodiment,resistance is measured between multiple pairs that share a givenconductive electrode 701. Not all the conductive electrodes areindicated by a reference numeral to avoid clutter, but each is labeledwith a respective letter. Here, conductive electrode pair A-B is usedfor a resistance measurement through a respective fluid column 702.Further, conductive electrode pairs A-D and A-C are also used for aresistance measurement through a respective fluid column 702 pluschannel element 703 and a respective fluid column 702 plus channelelement 703 plus fluid column 702, which form respective longer fluidpaths. The same may be done with conductive electrode pairs B-C, B-D,and C-D. Given known properties of the respective channels, which may bestored explicitly or tacitly (e.g., by way of a formula or look uptable), the fluid conductivity can be derived from these resistancemeasurements. Further measurement columns 702, receiving the same fluid,may be added to provide additional fluid paths between additionalconductive electrode pairs, such as A-E, A-F, E-F, E-H and so on.Additional conductive electrodes may also be added to each measurementcolumn such as the conductive electrodes labeled J through M in FIG. 9B.In the latter example, additional conductive electrodes 708 formingpairs can be used for additional measurements of fluid conductivity, forexample, A-J and A-K. Not all combinations of conductive electrodes areenumerated herein as it is straightforward to make a comprehensive listof conductive electrode pairs that can be formed with any such aconductivity measurement system based on a desired number and allocationof conductive electrodes. As in the embodiment of FIG. 9A, branch linesthat admit diluent or concentrate may be included at any point, ofcourse with diminution of the number of combinations of conductingelectrodes that may be available for conductivity measurement.

In the foregoing embodiments, by forming multiple electrical conductionpaths through interconnected conductivity cells, using additionalconductive electrodes for each measurement column, and/or by measuringacross fluid paths between measurement columns, additional measurementsof the same fluid conductivity or measurements that include additionalvariables such as the electrode “wet-side resistance,” i.e., theresistance between an electrode and the fluid can be better gauged, atleast for purposes of determining the reliability of a conductivitymeasurement. Where a resistance measurement appears faulty due to anunexpected resistance associated with an electrode, the multiple pathsprovide multiple equations to solve for the unknown additionalresistance correction term that is used to compensate the resistance.The controller may perform these calculations automatically.

In any embodiments, an accumulator, such as accumulator 502, can beomitted and an inline pressure sensor alone may be employed therebyrelying on the compliance of tubing for providing smooth pressuresignals for control. The elimination or reduction in size of theaccumulator may be an optimization variable. Reducing this volume mayspeed the synchronization process.

In any of the embodiments, including the claims, two medicamentconcentrates may be diluted by a medicament proportioning system ormodule. In these arrangements where there is concentration detection,the buffer may be diluted first and then the acid may be diluted to forma dialysate or replacement fluid product. This has benefits in that theconcentration signal of the acid is stronger than that of the dilutebuffer thereby causing more sensitive concentration detection.

In any of the embodiments including cycler 106, the latter may bereplaced by any medicament consuming device or article such as a storagecontainer for product medicament or a peritoneal dialysis cycler. In anyof the foregoing embodiments, a pressure sensor may be positioned withinan inlet or outlet of the accumulator to allow the controller to controlflow through the accumulator. This may in effect be a mechanicalpressure control signal from the device that demands fluid from any ofthe disclosed medicament proportioning system, medicament proportioningmodule, or other device.

In any of the foregoing embodiments, the flow channels and pumpingmechanisms may be replaced with any equivalent elements adapted forfluid conveyance. They may be selected to handle flow rates in therange, in respective systems or in a single system to provide medicamentto a consuming device at a rate of 25 through 400 ml/min. Any of theembodiments may be modified to provide an intermediate storage ofmedicament if the instantaneous demand of a consuming device exceeds theselected maximum generation rate of medicament. The medicament formed bythe foregoing embodiments may be dialysate or replacement fluid for useany type of renal replacement therapy system, for example, peritonealdialysis, hemodialysis, liver dialysis, and hemofiltration. Theconsuming appliance for any of the above systems may be a storagecontainer to generate medicament to support a vacationing patient. Itwill be observed that in the embodiments disclosed, spent fluid (e.g.,spent dialysate) from an attached cycler can be disposed of such that itnever enters the medicament proportioning module 104 or any elementupstream of the cycler. In embodiments, the cycler 106 is configured toprevent a backflow of fluid into the medicament proportioning module104. For example, a check valve may be provided in-line between themedicament proportioning module 104 and cycler 106 for such a purpose.

By providing ultrapure water that has been reliably sterilized andguarded against touch contamination, it is possible to ensure againstrisk for a primed medicament proportioning module 104 to treat multiplepatients within a long time period, in an exemplary embodiment, up to 24hours apart. Also, the medicament proportioning module 104 may be primedand readied for a treatment to occur many hours, for example up to 24hours, from the time of set-up.

In any of the foregoing cartridge embodiments, the cartridge may includea data carrier (e.g., 519) which may be or incorporate devices such as abar code, RFID, smart chip, memory chip, or other device that includesdata related to the concentrate or dry compound attached thereto forgeneration of medicament. Thus, by installing the cartridge, detailsrelated to the attached medicament concentrate can be communicated tothe controller of the medicament proportioning module 104 or medicamentpreparation system (e.g., 600). For example, the data carrier mayinclude data responsive to an expiration date, whether the fluid circuitattached to the cartridge has been used prior to the most recentinstallation, how much fluid has been generated from it, how long sinceit was first primed with fluid, the makeup of the concentrates attachedto the fluid circuit. The pre-attachment of the concentrates to thecircuit cartridge (e.g., 500, cartridge 406 and others), when thecartridge includes a data carrier that refers to information about theconcentrates and other components of the fluid circuit, provides the twobenefits (1) of allowing the cartridge, which may be of a types that isregistered in a specific position and therefore convenient to allow forreading of data on the data carrier by means of a reader and (2)preventing contamination of fluid circuit by avoiding the need to make anew connection to combine the concentrate containers with the otherelements of the fluid circuit. The precise positioning of the cartridge,for engagement of actuators and sensors therewith, can ensurepredictable and reliable interaction between the data carrier and areader co-located with the sensors and actuators. Also, the cartridgemay be of a type that is convenient and relatively small, makinghandling easier for less able-bodied users, since the cartridge may betethered to the heavier concentrate containers which may be placed inseparate positions and, in embodiments, with less accuracy. Inembodiments, a receiving support for the concentrate containers may below down next to the floor while the cartridge receiving position may belocated above that receiving support for the concentrate containers. Forexample the medicament concentrate disposable package, which may containthe medicament concentrates as discussed with reference to the variousembodiments, is positioned on a low shelf. A slide out tray (on rollerrails for example) may be provided (not shown) to allow the medicamentconcentrate disposable package to rested thereon so that the medicamentconcentrate disposable package can be pushed into position withoutsliding. Similarly, for the ultrafilter module and any other similarcomponents.

The controller of the medicament proportioning module 104 or medicamentpreparation system 700A, 700B, or any other of the modules or systemsherein described may have an identifier of one or more patientscorrelated with the medicament that is prescribed for that patient. Thedata included in the data carrier may be used by the controller toconfirm that the correct fluid circuit is loaded by verifying thecircuit cartridge data carrier. The control of the proportioning bypumps may be regulated to conform to the required medicament product.When the cycler is attached to the medicament preparation system (e.g.,600) or module 104, a signal communication between the controller of themedicament proportioning module 104 or medicament preparation system700A, 700B and the attached consuming device, such as cycler 106 (e.g.,see lines 124) may contain data indicating the type of medicamentrequired, an identification of the patient, a prescription, or otherinformation that may be correlated by any of the controller with theparameters of the connected fluid circuit as indicated on the datacarrier of the cartridge and a signal indicating permitted ornon-permitted component installation generated by any of thecontrollers. Such a signal may cause the generation of an outputindication or prevent further operation of the equipment, if anon-permitted component installation is performed.

The data carrier may also establish expected reading ranges for measuredconcentration of medicament concentrate indicated by concentrationmeasurement module 535A-535D. These data may be used to control thedilution rate of the respective medicament concentrates using feedbackcontrol from the concentration measurement modules orconductivity/temperature sensors in accord with the respectiveembodiments. Note that as used herein, a combination of a conductivitysensor and a temperature sensor may also be referred to as aconcentration measurement module. The data carrier may includecalibration data or data used for ensuring the accuracy of measurementusing the cartridge or other parts of the fluid circuit. For example, inembodiments, the data carrier may communicate to the controller the cellconstants or dimensions of the conductivity sensors of the cartridge foruse in computing conductivity and thereby concentration. The datarelating to disposables attached to and used with the system (e.g.,water purification module 102 and medicament proportioning module 104)may be logged in a maintenance and/or procedure log for troubleshootingand service. The latter may be output by the user interface bymaintenance, treatment, or service personnel. Solute concentration isused to set target conductivity values. Reading-in solute concentrationallows addition of new catalogue numbers without requiring a softwareupdate.

The replaceable components used for water purification may includereplaceable tagged components with data carriers permitting varioussimilar functions as the data carriers described herein and otherrelevant to the cartridge. Generally, the function of the waterpurification module 102 (or the water purifying function of anintegrated medicament preparation system), is to purify water to a samestandard. However, the performance characteristics of the replaceabletagged components may vary. The control of the water purification module102 may include determining whether the replaceable tagged component iscorrect for the particular water purification module 102. Inembodiments, the controller may predict a total amount of fluid that maybe processed before replacement of certain replaceable tagged componentsis appropriate.

Referring now to FIG. 9A, a conductivity measurement portion 700A of afluid circuit includes multiple measurement columns 702 connected inseries by channel elements 703, 705, 707. Additional junctions may beprovided as described with reference to FIG. 10. Four pairs ofconductive electrodes A-B, C-D, E-F, G-H, are shown but the number ofcolumns and number of electrodes can vary. As described with referenceto FIG. 10, each conductive electrode pair can be used for anindependent measurement of a conductivity of fluid (or fluids) flowingtherethrough. In the present embodiments, resistance is measured acrossother pairs of conductive electrodes than the pairs, A-B, for example,at opposite ends of each measurement column 702. For example, theresistance between conductive electrodes A-C and A-D as well as B-C andB-D may also be measured. With predefined channel properties betweenthese pairs of conductive electrodes stored in a controller (oreffectively stored in a lookup table or formula for computing fluidconductivity, multiple equations with multiple unknowns that include thecontact resistances of the electrical contacts used to measureconductivity can be obtained.

In any of the foregoing embodiments, fluid circuits may include inlinechambers (accumulators) to reduce water hammer due to interactionbetween interconnected peristaltic pumps. Additional lengths of tubingmay also be included for the same purpose. Also, tubing diameters ofpump tubing segments may be selected to minimize interaction issueswhich may reduce accuracy or cause breakage of circuit elements.

In any of the disclosed embodiments that measure the conductivity of afluid by using conductivity cells, conductivity sensors, or conductivitymeasurement modules (e.g., 415, 416, 417, 418 in FIG. 8A, 535A-D in FIG.6, or 535 in FIGS. 7A-7D), electrical contact with wetted electrodes(e.g., 505, 506, 510, 512 in FIG. 8A, 550, 577 in FIGS. 7A-7D, or 808 inFIGS. 8A, 8B) may be made through elastomeric contacts instead ofspring-biased contacts. An embodiment of an elastomeric contact insertis shown in two oblique views 710 a and 710 b in FIGS. 10A and 10B,respectively. The contact insert is configured to be inserted into ahousing that exposes the top side and the bottom side of the contactinsert such that the top side of the elastomeric contact can makeelectrical contact with appropriate electrical point/points in anelectrical circuit of a conductivity measurement module, while thebottom side of the elastomeric contact can make electrical contact witha wetted electrode (further details of embodiments of the housing aredescribed below with reference to FIG. 13A and 13B). As compared tospring-biased contacts, using the disclosed elastomeric contacts allowsfor positional tolerance, for example, at least along the Z axis 718.Further, the disclosed elastomeric contacts are less susceptible tofluid leaks as compared to spring-biased contacts such as pogo pens.This is due to the fact that pogo pens have sliding surfaces (to slidethe pen to make contact with wetted electrodes) while the disclosedelastomeric contacts include no sliding surfaces.

Still referring to FIGS. 10A and 10B, in one embodiment, the contactinsert is formed by wrapping (along the Y axis 720 and the Z axis 718)at least a portion of an elastomeric block 714 with a parallel array ofelectrically conductive wires 712, where each two adjacent wires areseparated by an electrically insulating material. Alternatively, thecontact insert may be formed by attaching/gluing/molding a ZEBRA®connector strip (i.e., an elastomeric connector strip with alternatingelectrically conductive and electrically insulating regions in anelastomeric matrix) around at least a portion of the elastomeric block714. The ends of the wires 712 may be protected by an adhesive protector716, for example, an adhesive film. The elastomeric block 714 may be ofany suitable elastomeric material such as silicon, rubber, syntheticrubber, or other material. The elastomeric block 714 is preferably of anelectrically insulating material. The wires 712 may be bonded to theelastomeric block 714. The wires 712 may be of any electricallyconductive material. In embodiments, the wires 712 are 0.002″ indiameter and made of gold over nickel-plated copper.

FIGS. 11A and 11B respectively show two oblique views 730 a and 730 b ofan embodiment in which the elastomeric block 714 has a relief recess 732that allows for improved positional tolerance along the Z axis 718. Thatis, the relief recess 732 permits the elastomeric block to better flex.The wires 712 span the relief recess 732 at the corresponding side ofthe elastomeric block 714. The shape, size, and location of the reliefrecess 732 in FIGS. 11A and 11B represent only one possible embodimentfor improving flexibility of the elastomeric contact, and alternativeshapes, sizes, locations, and numbers of relief recesses will beapparent to a skilled person in the relevant arts.

FIGS. 12A, 12B, and 12C respectively show cross-sectional views 734 a,734 b, and 734 c (orthogonal to the X axis 709) of example embodimentsof variations of the disclosed elastomeric contact. The elastomericblock 714 of the elastomeric contact insert illustrated in FIG. 12A issolid, while the elastomeric block 714 of the elastomeric contact insertillustrated in FIG. 12B has cutouts 736 to provide springiness, and theelastomeric block 714 of the elastomeric contact insert illustrated inFIG. 12C has both the relief recess 732 and the cutouts 736 to providebetter flexibility and springiness.

FIGS. 13A-13D show various views 750 a, 750 b, 750 c, and 750 d ofembodiments of a housing 752 that supports an elastomeric contact insert754 for use. More specifically, FIGS. 13A and 13B show oblique views 750a and 750 b of the housing 752 with the elastomeric contact insert 754inserted, FIG. 13C shows a cross-sectional view 750 c of the housing 752without the elastomeric contact insert 754 being inserted, and FIG. 13Dshows a cross-sectional view 750 d of the housing 752 with theelastomeric contact insert 754 being inserted. The housing 752 may be ablock of rigid plastic or other electrically insulating material. Inembodiments, the housing is of silicone. The elastomeric contact insert754 is configured to be inserted in a receiving well 756 of the housing752. The resilience of the elastomeric contact insert 754 allows forvariations in the smoothness of the receiving well 756 to beaccommodated. Adhesive may be inserted in the receiving well 756 priorto the insertion of the elastomeric contact insert 754.

In one embodiment, the elastomeric contact insert 754 and the receivingwell 756 of the housing 752 are configured such that when theelastomeric contact insert 754 is inserted in the receiving well 756,the top portion of the housing 752 snugly fits the top portion of theelastomeric contact insert 754 while the bottom portion of the housing752 is wide enough to allow for a void space being created between theinner surface of the bottom portion of the housing 752 and the outersurface of the bottom portion of the elastomeric contact insert 754.

In one embodiment, the elastomeric contact insert 754 is inserted suchthat a top surface 758 of the elastomeric contact insert 754 slightlyprotrudes from the top portion of the housing 752, while a bottomsurface 760 of the elastomeric contact insert 754 slightly protrudesfrom the bottom portion of the housing 752.

In one embodiment, once the elastomeric contact insert 754 is inserted,an array of wires at the top surface 758 of the elastomeric contactinsert 754 are configured to make electrical contact with a wettedelectrode in a conductivity measurement module when the housing 752 isforced against the wetted electrode. Further, an array of wires at thebottom surface 760 of the elastomeric contact insert 754 are configuredto make electrical contact with wires or printed circuit board (PCB)traces that are forced against the bottom surface 760 of the elastomericcontact insert 754, where the PCB traces may in turn be soldered orotherwise electrically connected to a sensor. As described herein withreference to various embodiments, for example, in FIGS. 13A, 13B, 13C,and 13D, each wire in the array of wires at the top surface 758 of theelastomeric contact insert 754 is electrically connected to acorresponding wire in the array of wires at the bottom surface 760 ofthe elastomeric contact insert 754. By pressing the top surface 758 ofthe elastomeric contact insert 754 against a flat wetted electrode andat the same time pressing the bottom surface 760 of the elastomericcontact insert 754 against the PCB traces, the array of wires providesredundant points of electrical contact between the wetted electrode andthe sensor. Accordingly, the housing 752 and the elastomeric contactinsert 754 form a contact device that is part of a fluid managementsystem with associated electronics for completing the sensor as well asother elements.

In embodiments, the sensor may be a fluid conductivity cell of adisposable fluid circuit having wetted electrodes that are pressedagainst the elastomeric contact insert 754 when installed. Inembodiments, the sensor may include driving and detection circuitry of aconductivity measurement electrical circuit such as a 4-terminal sensingcircuit as described below with reference to FIG. 5.

FIG. 14 shows a schematic view 770 of various components forming a4-terminal sensing circuit in a fluid conductivity cell of a disposablefluid circuit in order to measure the conductivity of a fluid that is incontact with a first wetted electrode 773 and a second wetted electrode771, according to an embodiment. 4-terminal sensing, also known asKelvin sensing, refers to a method of measuring the electrical impedancebetween two points by driving current between the two points via acircuit formed between the first PCB current contact 778 and the secondPCB current contact 782 while measuring the voltage between the firstPCB voltage contact 780 and the second PCB voltage contact 784.Accordingly, since the induced current does not go through the contactsthat are used for measuring voltage, the impedance of the voltagemeasurement contacts cannot induce errors in the impedance measurement,and the impedance measurement is insensitive to contact resistance inthe current portion of the circuit.

As shown in the embodiment of FIG. 14, 4-terminal sensing is implementedby a current source 772 and a voltmeter 774 that are both electricallyconnected to respective electrodes in a PCB 776, where the PCB 776 is inelectrical contact with the first wetted electrode 773 and the secondwetted electrode 771 via a first elastomeric contact insert 786 and asecond elastomeric contact insert 788, respectively. The current source772 drives an electrical current between a first PCB current contact 778and a second PCB current contact 782 on the PCB 776, while the voltmeter774 measures the voltage difference between a first PCB voltage contact780 and a second PCB voltage contact 784.

The PCB 776 is pressed or held against a first side 796 of the firstelastomeric contact insert 786 and a first side 798 of the secondelastomeric contact insert 788 such that:

-   -   a first group of parallel wires 790 on the first elastomeric        contact insert 786 make electrical connection with the first PCB        current contact 778 on the PCB 776,    -   a second group of parallel wires 792 on the first side 796 the        first elastomeric contact insert 786 make electrical connection        with the first PCB voltage contact 780 on the PCB 776,    -   a first group of parallel wires 794 on the second elastomeric        contact insert 788 make electrical connection with the second        PCB voltage contact 784 on the PCB 776, and    -   a second group of parallel wires 795 on the second elastomeric        contact insert 788 make electrical connection with the second        PCB current contact 782 on the PCB 776.

In one embodiment, the first PCB current contact 778 and the first PCBvoltage contact 780 may be printed on the PCB 776 as a pair of adjacentparallel rectangular contact pads, collectively covering an area smallerin area than, or approaching the area of the first elastomeric contactinsert 786 that in contact with the PCB 776. Similarly, the second PCBcurrent contact 782 and the second PCB voltage contact 784 may beprinted on the PCB 776 as another pair of adjacent parallel rectangularcontact pads, collectively covering an area smaller in area than, orapproaching the area of the second elastomeric contact insert 788 incontact with the PCB 776.

In the embodiment of FIG. 14, all PCB electrodes are printed on the samePCB 776. However, in alternative embodiments, the PCB electrodes may beprinted on more than one PCB. For example, in an alternative embodiment,the first PCB current contact 778 and the first PCB voltage contact 780may be printed on a first PCB, while the second PCB voltage contact 784and the second PCB current contact 782 may be printed on a second PCBdifferent than the first PCB. In this alternative embodiment, the firstPCB is forced against the first elastomeric contact insert 786, whilethe second PCB is forced against the second elastomeric contact insert788.

A second side 797 of the first elastomeric contact insert 786 is forcedagainst the first wetted electrode 773, so that both the first group ofparallel wires 790 and the second group of parallel wires 792 makeelectrical connection with the first wetted electrode 773. Similarly, asecond side 799 of the second elastomeric contact insert 788 is forcedagainst the second wetted electrode 771, so that both the first group ofparallel wires 794 and the second group of parallel wires 795 makeelectrical connection with the second wetted electrode 771. As a result,the current source 772 is in effect driving a current across the fluidin between the first wetted electrode 773 and the second wettedelectrode 771, and the voltmeter is in effect measuring the voltage dropacross the fluid in between the first wetted electrode 773 and thesecond wetted electrode 771. Accordingly, fluid conductivity may bedetermined as a linear function of the driven current value divided bythe measured voltage value.

In any of the embodiments, the PCB 776 may provide test points formeasuring the integrity of the electrical connections made between thePCB electrodes, the elastomeric contact inserts, and the wettedelectrodes, as will be apparent to a skilled person in the relevantarts. Also, the resistance of the connection between the contacts and arespective electrode can be confirmed by a controller by applying acurrent between the first or second PCB current contact and its adjacentvoltage contact and measuring a voltage drop. If a resistance above athreshold level is detected, the controller may generate an erroroutput.

FIGS. 15A and 15B show cross-sectional views 600 a and 600 b of analternative housing 602 that can support the elastomeric contact insert754 in embodiments. The elastomeric contact insert 754 may be insertedalong the direction indicated as 604 into a receiving well 606 of thehousing 602. The insertion places the parallel wires 608 of theelastomeric contact insert 754 in electrical contact with a firstelectrical housing contact 610 and a second electrical housing contact612 provisioned on the surface of an internal wall of the receiving well606. A first electrical housing contact 614 and a second electricalhousing contact 616 may be electrically connected to a respective one ofthe first electrical housing contact 610 and the second electricalhousing contact 612 to provide electrical connection access torespective ones of the first electrical housing contact 610 and thesecond electrical housing contact 612 from outside the housing 602. Thefirst electrical housing contact 610 and the second electrical housingcontact 612 may be made of machined bores in the internal wall of thereceiving well 606 of the housing 602 and may be round or have any othershape rather than being rectangular as illustrated.

Once inserted, each wire in an array of wires on a top surface 618 ofthe elastomeric contact insert 754 is electrically connected to arespective one of the first electrical housing contact 610 and thesecond electrical housing contact 612, and thus is also connected to arespective one of the first electrical housing contact 614 and thesecond electrical housing contact 616. The first electrical housingcontact 614 and the second electrical housing contact 616 may in turnhave wires or PCB traces connected to them which may then be soldered toa device such as driving and detection circuitry of a sensor asdescribed herein with reference to various embodiment. A wettedelectrode may then be forced against the top surface 618 of theelastomeric contact insert 754, thereby allowing for electricalconnections to be made between the wetted electrode and both of thefirst electrical housing contact 614 and the second electrical housingcontact 616. Accordingly, the housing configuration shown in theembodiment of FIGS. 15A and 15B may be used to implement 4-terminalsensing for fluid conductivity measurement as described herein withreference to FIG. 14.

Referring to FIG. 16, a medicament preparation system 1600 includes afluid circuit 1601. In the example of FIG. 16, the medicamentpreparation system 1600 is formed on a cartridge of a dialysis system,but system 1600 is not limited to this exemplary embodiment. In anembodiment, the cartridge may be the same as cartridge 500 inembodiments above. Embodiments disclosed below are also applicable innon-cartridge based fluid circuits, where two flow paths come togetherand where it is desirable to control the quantity of fluid in each flowpath.

In the example of a cartridge, the cartridge may be rigid, thus forminga rigid fluid path on or within the cartridge. Thus, the fluid circuit1601 may be formed in a rigid structure. The cartridge may be adisposable component of a dialysis system, or may be a part of adisposable component.

It will be understood that the present disclosure is not limited to afluid circuit on cartridge, and other types of fluid circuits 1601 arecontemplated by this disclosure. The cartridge 1607 may be a disposablecomponent of a fluid machine, such as a dialysis machine, or may be apart of such a disposable component that includes tubes and other parts.In some embodiments the cartridge may be pre-connected to container ofconcentrated substance such that the cartridge, the connection to theconcentrate container, and the concentrate container are all sterilizedtogether.

The fluid circuit 1601 shown in FIG. 16 may take various shapes andforms, and the particular arrangement is only exemplary. The fluidcircuit 1601 includes one or more junctions 1602 and 1603, as shown inFIG. 16. The junctions are oriented in a particular position relative tothe force of gravity, and the entire fluid circuit may be oriented in apredefined way relative to the force of gravity when installed in areceiving portion of a fixed machine such as a fluid preparation system(not shown). In an embodiment, when the fluid circuit 1601 is in use,such as when mixing fluids, the junctions 1602 and 1603 are positionedsuch that a trough or valley 1704 is formed at the lowest position ofthe junction. An enlarged view of an example of junction 1602 is shownin FIG. 17, and an enlarged view of an example of junction 1603 is shownin FIG. 18.

Referring to FIG. 17, the junction 1602 may be generally “Y” shaped,where the left upper branch of the Y and the lower channel 1707 branchform common channel 1707. It is contemplated that the channel 1707carries a fluid with a particular density. In an exemplary embodiment,the fluid is purified water mixed with some medicament. In anotherembodiment, the fluid is a mixture of purified water and bicarbonate. Inanother embodiment, the fluid is a diluted dialysate.

The upper right branch of the junction 1602 is formed by concentratechannel 1706, which carries a fluid with a density that is greater thanthe density of the fluid in the common channel. The relative differencein the density, together with a chicane formed in the concentratechannel 1706 and described below will be appreciated when consideringthe operation of the medicament preparation device. In embodiments, thefluid flowing through channel 1707 has different viscosity than thefluid flowing through channel 1706, such that the fluid in channel 1706has a greater viscosity.

As noted above, the medicament preparation system 1600 is used to createa medicament by admixing two fluids. In an exemplary embodiment,dialysate is produced by admixing purified water with a dialysateconcentrate. To mix the two fluids, a mechanism, such as a pump, moveseach of the fluids through the two upper branches of the junction. Insome embodiments, the pump may be a peristaltic pump (not illustrated)that exerts force on a pumping segment to move the fluid(s) through thefluid circuit 1601. FIG. 19 illustrates flow 1901 of a diluent, or otherfluid, in channel 1706 and concentrate flow 1902 in channel 1707.

Staying with the example of producing dialysate, channel 1707 will befilled with purified water (or water with other chemicals mixed in, suchas bicarbonate). The concentrate channel 1706 will be filled with afluid that has a higher density that the fluid in the channel 1707 (forexample concentrated dialysate or acid).

As shown in FIG. 17, the concentrate channel 1706 has a chicane 1701that curves sharply upward and then sharply downward before theconcentrate channel 1706 meets the common flow channel 1707. The chicane1701 can be created by a lower protrusion 1703 extending upward from thefloor 1710 of the concentrate channel 1706 and an upper protrusion 1702extending from the roof of concentrate channel 1706. The chicane alsoincludes a valley 1704 as shown in FIG. 17. By providing that the higherdensity fluid must flow upward in order to passively flow into thecommon channel, the chicane acts as a fluid gravity trap.

When the common flow channel 1707 is filled with a first fluid and theconcentrate channel 1706 is filled with a second fluid, and the junction1602 is oriented as shown in FIG. 17 (relative to the force of gravity),it can be appreciated that the first fluid and the second fluid meet atthe junction 1602. Because the second fluid has a higher density thatthe first fluid, the second fluid fills the valley 1704, but without apumping force, will not flow over the upper edge of lower protrusion1703 due to its higher density compared to the first fluid. In otherwords, the chicane 1701 prevents gravity siphoning or mixing of thesecond fluid into the common flow channel 1707 and concomitant mixingwith the first fluid. When mixing is desired, pumping force is appliedto convey the second fluid through the concentrate channel 1706 into thecommon flow channel 1707. Likewise, pumping force may be applied to thefirst fluid to accurately meter an appropriate amount of each fluid intothe mixture. As shown in FIG. 16, the first fluid can come from diluentsupply 1605, while the second fluid may come from concentrate supply1606. A feature that aids in the prevention of mixing is also thediameter of the channels relative to the viscosity of the fluids.Smaller diameter tubing helps to prevent mixing when the pump isstopped.

Referring to FIG. 18, another embodiment of junction 1603 is shown. Thejunction 1603 is different in the shape of the upper protrusion 1802 andthe shape of the concentrate channel 1806. The upper protrusion 1802lies substantially parallel to the lower protrusion 1803, but may beoriented at other angles as well. The upper protrusion 1802 extends awayfrom the roof of the concentrate channel 1806 at an angle, which isimposed by the shape of the roof. The height of the concentrate channel1806 is not constant, in contrast to the concentrate channel 1706. Theconcentrate channel 1806 widens as it approaches the upper protrusion1802, creating a larger cross sectional area than farther upstream. InFIG. 18, diluent is provided from diluent supply 1605 and flows left (inFIG. 18) and up. Concentrated fluid flows through concentrate channel1806 and is admixed with the diluent when the concentrated fluid ispumped through the concentrate channel 1806.

FIGS. 19-22 illustrate schematic examples of the junctions 1602 and1603. These figures can be thought of as cross-sectional views of theflow paths. While no particular shape of the flow channel is shown, itis contemplated that the concentrate channel 1706 and 1707 may becircular, oval, rectangular, or rounded rectangular in cross sectionalshape.

Referring still to FIG. 19, the interaction between water (possibly withbicarbonate added) and an acid at a junction 1602 is shown. The waterflow 1901 flows through channel 1707, while the concentrate flow 1902flows through channel 1706. In this example, the concentrate is an acid,illustrated as a slanted line pattern. The water and acid is mixed toproduce dialysate. The acid has a higher density than water, and thusremains in the valley 1704 unless sufficient pumping force is applied tothe acid to raise it over the lower protrusion 1703 of junction 1602.The flow in FIG. 19 is the same as in FIG. 17, downward as indicated byarrows 1901 and 1902.

Referring to FIG. 20, the junctions 1602 and 1603 may include allfeatures of FIG. 19, and also an overhang 2001. The overhang 2001 can beprovided to reduce or avoid turbulence in flow 1901 through channel1707. As would be understood, the overhang 2001 has a sufficient lengthto shunt fluid in channel away from channel 1706. The length of overhang2001 can be set based on expected flow rate of flow 1901 and theexpected back pressure in channel 1706, which naturally opposes theingress of fluid from channel 1707 into channel 1706.

Referring to FIG. 21, a flap 2101 may be added in addition or instead ofoverhang 2001. The flap 2101 can be biased such that biasing force keepsthe flap 2101 closed until sufficient pressure builds up in channel1706, at which point the flap permits fluid from channel 1706 to flowand mix with fluid in channel 1707. The flap 2101 is illustrated as aseparate element with a hinge pin, but the flap 2101 can be molded atthe same time as the flow channel, and can be made of a material thatprovides the necessary biasing force to keep the flap 2101 normallyclosed. The flap 2101 can be made of the same material as the rest ofthe flow channel, and the biasing force is controlled by selecting aparticular thickness for the flap 2101. In embodiments, the flap 2101can be made of a different material than the rest of the flow channel,and it is molded in a two-step molding process so that the flap 2101 canmove and flex relative to the rest of the flow channel structure. Inembodiments the flap is coated with a hydrophobic coating that reducesthe likelihood of the concentrate from sticking to the flap 2101.

FIG. 22 illustrates an embodiment where the flap 2201 may be larger thanthe flap 2101, and the lower protrusion 1703 is not present. The upperprotrusion 1702 may also be absent in this embodiment. The flap 2201 isbiased to keep the concentrate channel 1706 closed, but the biasingforce is overcome when fluid in the concentrate channel 1706 is pumpedtoward the channel 1707.

Build-up of chemical and biological material in waste lines and drainsused in medical application can require premature replacement orextensive cleaning using aggressive chemical. This is often expensive,burdensome, and can result in exposure of the user to harmful chemicals.The disclosed embodiments include devices and methods for preventing orat least delaying waste build-up that would negatively affect systemoperation. This is particularly important in applications where thewaste fluid has high hardness that can result in calcium carbonatedeposit. Examples are reverse osmosis, electro-deionization, andcapacitive deionization reject water.

FIG. 23 shows a water purification system 2300 which may be based onreverse osmosis (RO) electro-deionization (EDI), or capacitivedeionization (CDI) all of which are examples of purification processesthat generate a waste water product that is highly concentrated insolutes and therefore subject to precipitation of solids on the internalwetted walls of the drain lines. In FIG. 1, raw input water enters thesystem through inlet 2301, the raw input water is purified, producingpurified product water and waste water. The purified product water exitsthrough product water outlet 2303 while the waste water exits throughwaste water outlet 2305. It should be understood that this discussionalso applies to other drain lines, such as drain line 545 describedabove.

In embodiments of the disclosed subject matter, the pipe, tube, conduit,channel that conveys waste water from waste water outlet 2305 is treatedto make its normally-wetted surface hydrophobic. In embodiments, acoating is a fluoropolymer of tetrafluoroethylene. In embodiments, thecoating is Polytetrafluoroethylene (PTFE). In embodiments the coatingmay be hydrophobic and also oleophobic. This may reduce or delayscaling.

In embodiments, the drain is made to be replaced on a longer-termschedule than other fluid handling elements such as filters and fluidcircuit connections. The RO (or EDI or) CDI device may have a controllerthat generates a reminder on a user interface to notify personnel toreplace the drain line on a different (longer-term) schedule than forreplacing the raw and product water handling circuit.

According to embodiments, the drain line may be treated with chemicalsthat prevent attachment of material to the wall of a permanent ordurable (i.e., long-term-use) waste line such as tube formed with ahydrophobic material. An example is known commercially as UltraEverDry.

FIG. 24 shows a cycler 2400 receiving medicament through inlet 2401.This inlet is expected to be less susceptible to fouling and buildup ofsolutes due to the purified nature of the medicament. The cycler 2400outputs waste fluid, which may be a mixture of the medicament andsolutes that were extracted from patient 2420 during treatment, throughdrain line 2405. The drain line 2405, similarly to waste water outlet2305 above, is at an increased risk of fouling and material buildup. Asshown in FIG. 24, treatment device 2410 receives medicament from cycler2400 through inlet port 2411, conveys the medicament to a consumerprocess (that may be connected to patient 2420) through patient access2421 and receives waste fluid through drain line 2425. The waste fluidis returned to the cycler through drain line 2415. In many treatments,such as peritoneal dialysis or hemodialysis, the waste fluid may containorganic material from the patient such as shed cells and proteins inspent dialysate. The organic material is susceptible to fouling andsticking to the drain lines that convey it. To mitigate such effects,one or more of the drain lines 2425, 2415, and 2405 can be coated with ahydrophobic and/or oleophobic coating as discussed above. In anembodiment, only drain line 2405 is coated with the hydrophobic and/oroleophobic coating, as it may be reused multiple times, while the drainlines 2425 and/or 2415 may be replaced at a greater frequency when thoselines are a part of a disposable fluid circuit used in medicaltreatments. In an embodiment, the drain lines 2425 and 2415 areconnected to the cartridge 1607, such that those drain lines are onlyused for the same number of treatments as the cartridge 1607. It isenvisioned that the cartridge 1607 can be used a single time for atreatment, such as hemodialysis of peritoneal dialysis, and then can bedisposed, along with the drain lines 2425 and 2415.

In other embodiments, the drain line's wetted surface may be providedwith texturing (not illustrated) that prevents adhesion such as nano ormicro textures known to have such effect. The texturing can be appliedinstead of, or in addition to, the hydrophobic and/or oleophobiccoating. Biomimetic surfaces that mimic the surfaces of butterfly wingsand shark skin have demonstrated such properties.

Referring now to FIG. 25, in further embodiments, the waste water outlet2305 and drain line 2405 can be made of elastic tubing 2503 thatcontracts and expands with pressure. The contracted state 2505 is shownwith a solid line, while the expanded state 2507 is shown with a brokenline in FIG. 25.

The contraction and expansion of the elastic tubing changes the shape ofinterior of the tubing and hence breaks deposits off the inner wall ofthe tubing. A pump 2501 having a characteristic that generates pressurepulses may be provided and connected to such a tube to cause theexpansion and contraction and thereby prevent scale buildup. The drawingis not to scale, and the effect of the contraction does not necessarilyoccur in the center of the tubing 2503, but can be spread along theentirety of the tubing. For example, the pump 2501 can generate pulsesat a specific frequency that may generate a standing wave in aparticular length of tubing 2503, such that expanded and contractedregions alternate along the length of the tubing 2503.

Referring to FIG. 26, the flexible tubing 2503 can be supported in arigid support 2601. The support 2601 may not be completely rigid, but itis less elastic than the tubing 2503. As shown in FIG. 26, the support2601 may include a body 2603 with cut-outs 2605, which providevisibility into the support 2601 and may also reduce the weight of thesupport 2601 and reduce manufacturing costs by reducing the amount ofmaterial needed.

FIG. 26 shows pump 2501 as in other embodiments, but the pump may beomitted and instead a different mechanism or force generator can applyforce to the tubing 2503 to cause its movement and change of shapewithin the support 2601. In an embodiment, the mechanism may apply atwisting force to the tubing 2503, which will cause the tubing tocollapse onto itself, but then return to the original shape when thetwisting force is reversed. This can be thought of as wringing thetubing 2503, and can be applied periodically or whenever the flow ratethrough the tubing 2503 is reduced. To this end, a flow rate monitor(not shown) may be provided to measure and report the flow rate to acontroller, which determines when to take steps such as wringing thetubing or operating the pump 2501.

Referring to FIG. 27, in an alternative embodiment, an active devicesuch as a vibrator or an actuator bends or vibrates a flexible draintube periodically to prevent or remove scaling. Tubing 2503 passesthrough holster 2701. While only a single holster 2701 is illustrated,multiple such holsters 3001 can be provided, as shown in FIG. 30.

A motor 2703 can be a linear motor that moves the holster 2701 fore andaft to cause bending of the tubing 2503. If multiple holsters 3001 areprovided, they can move in opposite directions and be driven by motor3003 through multiple drive shafts 3004 and 3006. The drive shafts 3004and 3006 may move in opposite directions to cause the tubing 2503 toflex in opposite directions to dislodge any accumulated or adhered onfouling matter. Alternative, a single motor 2703 can be linked to themultiple holsters 3001 by a cam-shaft system (not shown) to cause thealternating fore-aft movement.

In further embodiments, the drain channel 2815 is selectively flushedwith deionized water to reduce scaling and minimize the possibility ofbacterial or fungal growth. The drain channel 2815 may be permanentlyconnected to the proportioning or treatment system 2800, as opposed tobeing a component of a disposable unit. This embodiment may beimplemented for example in a system that consumes deionized water suchas a medicament admixing system shown in FIG. 28. Here concentrates C1and C2 are admixed to form a product fluid. Ultrapure water is pumpedthrough a common line, and may be provided from product water outlet2303 of the water purification system 2300. Concentrate, or partially orincompletely mixed, medicament may be selectively directed along channel1707 to the drain for testing by a sensor 2810 under control of a switchvalve 2805 controlled by a controller. At intervals, the control valvemay divert pure water from the ultrapure source to the drain to flushit.

Referring to FIG. 29, flushing deionized water may be done in a system2900 that does not ordinarily consume ultrapure water for other purposesby providing a source of deionized water (DI) connected to a controlvalve 2901 and used to flush a drain in the same way, as shown in FIG.28.

Referring to FIG. 31, a view of housing 3100 opening 3112 is shown. Thistype of a housing could be a part of the cartridge 500 and used tosecurely position a conductivity sensor. The housing may be a portion ofa flow through channel, a chamber, or any element that confines adetermined volume of a fluid whose conductivity is to be measured. Thehousing 3100 may be a part of a fluid circuit, for example one takingthe form of a disposable cartridge for a medical treatment device. Forpurposes of this disclosure, the specifics of the housing as a fluidcontainment device are not essential to understanding the structuresrelated to the assembly of an electrode 3200 to it including a steppedopening 3103 that secures and seals an insertable electrode 3200.

Referring now also to FIG. 32, which illustrates a cross-section view ofthe housing viewed along plane II-II in FIG. 31, opening 3103 is definedby riser 3108 extending axially from the housing 3107. In someembodiments the riser 3108 may be omitted or reduced in size, such thatthe opening 3103 is defined in the housing 3107 outer surface. In otherembodiments, a riser may extend into an interior of the housing 3107.The rise has a top surface 3101 that surrounds the opening 3103. In theillustrated embodiment the overall shape of the stepped opening 3103 iscircular, but the opening may have other shapes as well, as illustratedin the embodiments in FIGS. 34-36, infra.

Referring again to FIG. 32, the top surface 3101 defines the opening3103 which may be seen from FIGS. 31 and 32 to be stepped defining anouter opening portion 3111 an inner opening portion 3112. The outeropening portion 3111 is larger than the inner opening portion 3112. Theouter opening portion 3111 may have a rounded lip 3133 that forms aprogressively narrowing entry to the outer opening portion 3111 from theriser top surface 3101 to a sidewall 3131 of the outer opening portion3111. In embodiments, the axial section profile of sidewall 3131 may beperpendicular the cross-section profile of the riser top surface 3101,as shown in FIG. 32. However, in other embodiments, the axial sectionprofile of the sidewall 3131 may be sloped. In addition instead of therounded lip 3133, the entry to the outer opening portion 3111 may bebeveled or simply step-shaped.

The inner opening portion 3112 is defined by a sidewall 3132 which has alanding 3123 extending axially toward the outside of the housing therebydefining a trough 3120 between the end of the sidewall 3131 and alanding 3123 at the outside extend of the rim, as shown in FIG. 32. Thetrough 3120 may have a flat bottom as shown in FIG. 32, or a curvedbottom (not shown). The depth and width of the trough 3120 permitshavings or burrs to be received therein when the electrode 3200 isinserted. The dimensions are discussed with reference to FIGS. 37A and37B. The electrode 3200 may be of a material that is harder or morerigid than the housing 3100, so that pressing the electrode 3200 intothe outer opening portion 3111 may produce burrs or shavings 3901 debrisas an edge of the electrode 3200 scrapes against sidewall 3131. Theburrs or shavings 3901 occupy the trough 3120 such that they areretained in a position that cannot block the electrode 3200 from beingseated on the landing 3122, as shown in FIGS. 37B and 38B. The electrode3200 may have barbs as illustrated in FIGS. 38A and 38B, but in variousembodiments, the electrode 3200 can have smooth sides as shown in FIGS.37A and 37B.

Referring again to FIGS. 31 and 32, the landing 3123 forms a rim 3122 ofthe inner opening portion 3112. The landing 3123 may provide a supportagainst which a bottom surface 3220 of the electrode 3200 comes to rest.The landing 3123 ensures the electrode 3200 is consistently oriented ata precisely-defined axial position after insertion by providing aninterfering engagement with the electrode 3200 which seats against it.The landing 3123 has a finite radial width that may be selected toensure that it provides a positive stop and resists variable forces toprevent variation in the axial position of the electrode 3200. Afluid-tight seal may be provided but is not essential. An additionalfunction of the radial width of the landing 3123 is to define anelongate narrow fluid path 3710 (See FIG. 37B) between the housing 3107interior and the portion of the electrode overlying the landing 3123.

After the electrode 3200 is positioned with the bottom surface 3220resting against the overlying the landing 3123, an open space remainsbetween the radial edge of the 200 and the sidewall 3131 at locationsaround the sidewall 3131 that do not have a spacer 3140. This open spacemay be filled with an adhesive substance. The adhesive substance may bea glue or a sealant that cures into a solid or semi-solid form, or mayremain pliable even after curing. The adhesive may expand in volume as apart of the curing process, thereby filling any gaps between the bottomsurface 3220 and the landing 3123. The viscosity of the uncured adhesiveis selected to enable the adhesive to flow into the gap between thesidewall 3131 and the electrode. The adhesive may fill the trough 3120,and may seep onto the top surface of the electrode 3200. It may bedesirable to select the volume of the adhesive such that it does notseep onto the top surface, or at least not onto the entirety of the topsurface.

Although FIGS. 31 and 32 illustrate a circular embodiment, the housingis not limited to this shape. FIGS. 34-36 illustrate rectangular, oval,and triangular shapes.

Three spacers 3140 function to constrain the lateral (relative to theopening axis) position of the electrode 3200. The spacers 3140 may beevenly spaced around the perimeter of the opening 3103. A greater numberof spacers may be used in alternative embodiment. A smaller number ofspacers may cooperate with the walls of the opening to constrain theelectrode in further embodiments.

FIGS. 32 and 37A, 37B illustrate details of an embodiment showingspacers 3140. As seen in FIG. 32, spacer 3140 protrudes partially out ofthe sidewall 3131 of the outer opening portion 3111 and has asemi-circular profile. The general shape of each spacer 3140 may be ahemi-cylinder with an elongate portion 3142 and a rounded end 3141. Thespacer 3140 can have other shapes consistent with the function describedherein, such as a flat bevel, conical shape, etc. The radial span of thespacer 3140 can be selected to constrain or over-constrain the electrodesuch that it is deformation or cut when the electrode 3200 slides alongthe space until it is seated on the overlying the landing 3123.

Advantageously, the provision of the spacers 3140 reduces the contactarea of the force of the sidewall against the electrode 3200 making iteasier to deform the spacers 3140. By permitting the spacers 3140 todeform or be cut with relatively low force, it possible to provide arelatively gentle over-constraint to the electrode 3200 to keep itcentered as it is advanced. The deformation engagement also helps tosecure the electrode 3200 axially after it seats against the landing3123.

Referring to FIG. 33, an embodiment of the housing 3100 includes amodified trough 3320 that does not extend around the entire perimeter ofthe opening 3103. Instead, the modified trough 3320 is formed only inthe vicinity of the spacers 3140 to accommodate burrs or shavings 3901.No burrs or debris 3901 are scraped off from the sidewall 3131.

The modified trough 3320 has a bottom 3327 and sidewall 3325 whichterminates at the sidewall 3131 of the outer opening portion 3111. FIG.33 illustrates the sidewall 3325 as sloping from the bottom 3327 up to amodified landing 3323. This embodiment provides maximum rigidity of thelanding 3323 due to the extra material present, and at the same timestill provides the advantages of the trough that accommodates burrs fromspacers 3340.

In an embodiment, the modified trough 3320 extends 5 degrees (measuredradially from the center of the outer opening portion 3111) on bothsides of each of spacers 3140. In another embodiment, the modifiedtrough 3320 extends 10 degrees, 15 degrees, 20 degrees, 25 degrees, or30 degrees on both sides of each of spacers 3140. The angular extensionof the modified trough 3320 can be selected based on the expected amountof burrs 3901 and debris from the spacers 3140 so that the modifiedtrough 3320 can accommodate all of the burrs 3901 and debris.

Turning to FIGS. 34-36, alternate embodiments of the opening may have arectangular, elliptical, or triangular shape. These shapes may encounterdifferent challenges than those of the round disc embodiment, butnevertheless benefit from spacers 3140. FIG. 34 illustrates anembodiment with a rectangular trough 3420, much like trough 3120 above.FIG. 34 also shows a rectangular landing surface 3423. It is noted thata sidewall 3425 is analogous to the sidewall 3125. However, the slope ofthe sidewall 3425 (and of the sidewall 3125) may be varied with otheraspects of the disclosed embodiments. To illustrate this point further,FIG. 35 shows an embodiment with an elliptical outer opening portion3511 and elliptical inner opening portion 3512. While this embodimentalso includes an elliptical or oval trough 3520 and a landing surface3523, the slope of the sidewall of the trough 3520 connecting to thesurface 3523 is perpendicular to the page, hence not visible in this topview. Such a steeply sloped wall may be desirable space is at a premium,as the resulting stepped opening can be made smaller than other designs.

Referring to FIG. 36, a triangular stepped opening includes a triangularouter opening portion 3611 and a triangular inner opening portion 3612.A triangular trough 3620 is similar to the other embodiments describedabove in terms of cross section, and can have varying slope of thesidewall (not visible in FIG. 36, as it portrays an embodiment with aside wall of the trough rising out of the page).

FIG. 37 illustrates dimensions of the cross-section of the spacer 3140as well as the overall stepped opening 3103. The distance from the lowersurface 3102 to top surface 3101 is represented at H1. The distance fromthe lower surface 3102 to the top of the spacer 3104 is represented asH2. The distance from the lower surface 3102 to the landing surface 3123is represented as H3. The distance from the surface of the bottom 3127of the trough 3120 is represented as H4. Thus, the height of the spacer3140 from the bottom 3127 is H2-H4, and must be less than H1.

Still referring to FIG. 37A, the distance from outer wall 3108 to innerwall 3131 of the outer opening portion is represented as d1. Thedistance from wall 3108 to the farthest point of the closes spacer 3140is represented as d2. Therefore, the thickness of the spacer 3140 isd2-d1, and is less than the width of the bottom 3127 of the trough 3120,as illustrated in FIG. 37. The distance from the wall 3108 to thefarthest end of the bottom 3127 is represented as d3. Therefore, thethickness of the bottom surface 3127 of the trough 3120 is given byd3-d1 in places without a spacer 3140, and by d3-d2 when radiallyadjacent to a spacer. Distance d4 represents the distance from the wall3108 to the boundary of the second sidewall 3125 of the trough and thetop surface 3123 of the landing 3122. It can be appreciated that varyingthe slope of the sidewall 3125 affects the thickness of the bottom 3127.If the sidewall 3125 is perpendicular to the lower surface 3102, d3becomes the same length as d4. The distance from the wall 3108 to thesidewall 3132 is represented as d5.

It has been found that certain ratios of the above-noted dimensionsproduce particularly desirable results.

Referring to FIG. 39, an alternative embodiment of the electrode 3300has a shape that, rather than using standoffs extending from theaperture to focus the forces for aligning and engaging the electrode,provides a similar effect by forming a non-round electrode that engagesthe walls of the aperture at predefined points. In an exemplaryembodiment, electrode 3300 has a substantially square profile withrounded corners, as shown in the dashed line in FIG. 39. The roundedcorners are the outer-most contact points of the electrode 3300 when itis inserted into an opening 3103, such that the rounded corners comeinto contact with sidewall 3131, as is shown in FIG. 32. While FIG. 32illustrates standoff 3140 along sidewall 3131, it is understood that thestandoffs 3140 may be omitted.

Referring to FIG. 40A, another embodiment of electrode 3400 has acircular profile, like electrode 3200, but may include spacers 3401. Thespacers 3401 may be an integral part of the electrode 3400, manufacturedas a part of the electrode 3400 during a casting and/or machiningprocess. However, the spacers 3401 may also be added, attached, ormachined into electrode 3400 at a later time, before the electrode 3400is inserted into the opening 3103. The spacers 3401 may be sized toextend radially outward from the electrode 3400 farther than thediameter of the sidewall 3131, such that the sidewall 3131 may be atleast partially deformed when the electrode 3400 is inserted.

The particular shape of the spacer 3401 may differ from that shown inFIG. 40A. For example, FIG. 40B illustrates an embodiment of electrode3402 that has spacers 3403 that have a more flat profile as compared tospacers 3401. Thus, spacers 3403 may have a larger contact area thatpresses against sidewall 3131, and may also be able to exert more forceonto that larger area without deforming.

FIGS. 40A and 40B show views that do not illustrate the extension of thespacers 3401 and 403 into the page. It would be understood that thespacers 3401 and 403 need not have the same height as the electrode. Inother words, the spacers 3401 and 403 may be formed on only a portion ofthe electrode 3400, 402 sidewall.

It may be advantageous for electrode 3400 to have three spacers 3401,but it is understood that a different number may be provided. In someembodiments, the electrode may have no spacers and spacers may beomitted from the opening 3103.

Referring to FIGS. 41A-B, the electrode 3305 includes no spacers, butmay include an annular barb 3308 and a recess 3312 at one end. Therecess 3312 is bound but upper surface 3318 of the electrode 3305. Asshown in FIG. 41A, the annular barb 3308 may have an outer diameter thatvaries along the height (vertical in FIG. 41A) of the barb. The uppersurface 3318 engages with a rim surface 3314 forming a seal when theelectrode 3305 is inserted into the opening 3306.

FIGS. 41A-B illustrate the electrode 3305 prior to insertion into orcoupling with a housing without any standoffs or spacers. The housing isas shown in FIG. 32, but includes no standoffs. FIGS. 41A and 41B can bethought of as FIG. 32 flipped upside down, with the electrode 3305 beinginserted from the bottom rather than from the top.

The housing in FIGS. 41A and 41B includes may include a riser 3301 witha bottom surface 3302. The height of the riser 3301 may vary toaccommodate the size of the electrode 3305. The bottom surface 3302defines the opening 3304 which may be seen from FIG. 41B to be steppeddefining an outer opening portion and an inner opening portion. Theouter opening portion is larger than the inner opening portion. Theouter opening portion may have a rounded lip or have a sharp edge. Inembodiments, the axial section profile of sidewall 3331 may beperpendicular the cross-section profile of the bottom surface 3302.However, in other embodiments, the axial section profile of the sidewall3331 may be sloped.

As would be understood from FIGS. 41A and 41B, when the electrode 3305is pressed into the housing, outermost edge of the annular barb 3308engages with the sidewall 3331 and the upper surface 3318 of theelectrode 3305 comes to rest against the surface 3314. This engagementmay form an air tight or fluid tight seal between the electrode 3305 andthe housing. Optionally, an adhesive or sealant may be added into thegap remaining between electrode 3305 and riser 3301 after the electrodeis inserted to create an airtight or fluid tight seal.

According to first embodiments, the disclosed subject matter includes amethod for measuring a conductivity in a fluid flowing in a fluidchannel. The method includes contacting a flowing fluid with twoelectrodes spaced apart across a portion of the fluid channel. Themethod includes contacting each of the two electrodes to a currentsource contact and a voltage measuring contact by creating a continuitybetween each of two respective portions of the each of the twoelectrodes and a respective one of the current source and voltagemeasuring contacts with multiple conductors.

In variations thereof the first embodiments include ones in which themultiple conductors are located on a surface of a resilient insulatingmember. In variations thereof the first embodiments include ones inwhich the creating a continuity includes squeezing the resilient memberfor each of the two electrodes between the each of the two electrodesand a respective combination of the current source and voltage measuringcontacts. In variations thereof the first embodiments include ones inwhich the insulating member and the multiple conductors form a Zebraconnector. In variations thereof the first embodiments include ones inwhich the contacting includes attaching the resilient member to thefluid channel. In variations thereof the first embodiments include onesin which the contacting includes attaching the resilient member to thefluid channel loosely such that it can move in a limited range along anaxis perpendicular to a surface of the each of the two electrodes. Invariations thereof the first embodiments include ones in which thecontacting includes attaching the resilient member to the fluid channelloosely by a housing such that it can move in a limited range along anaxis perpendicular to a surface of the each of the two electrodes. Invariations thereof the first embodiments include ones in which thecontacting includes attaching the resilient member to the fluid channelloosely by a housing partially surrounding the resilient member suchthat it can move in a limited range along an axis perpendicular to asurface of the each of the two electrodes. In variations thereof thefirst embodiments include ones that include measuring a resistance ofelectrical continuity between a voltage measuring contact and a currentsource contact to detect contact resistance. In variations thereof thefirst embodiments include ones that include performing Kelvin sensing byelectrical impedance between the two electrodes by driving currentbetween the them and measuring a voltage between them. In variationsthereof the first embodiments include ones in which the resilient memberand all multiple conductors constitutes an elastomeric contact insert ora compliant multiconductor element as described in the embodiments.

According to second embodiments, the disclosed subject matter includes aconductivity measurement system. A single-use fluid circuit has at leasttwo planar electrodes forming a part of a wall of a fluid channel suchthat the electrode has a wetted side facing an interior of the fluidchannel and a contact side opposite the wetted side. Flexibleelectrically-conducting elements are attached to the fluid channel eachwith at least one conductor thereof facing a respective one of theelectrode contact sides. A multi-use driver has a pair of electricalcontacts connected to a current source and a voltage sensor for each ofthe electrodes. The multi-use driver has a receiving member shaped toreceive the single-use fluid circuit fluid channel planar electrodes.The multi-use driving has a forcing member that opens to receive thesingle-use fluid circuit and closes to force each flexibleelectrically-conducting element between the each of the electrodes and arespective pair of the electrical contacts.

According to third embodiments, the disclosed subject matter includes aconductivity measurement system. A fluid channel has a first wettedelectrode and a second wetted electrode configured to directly contact afluid flowing in the fluid channel. A first contact device includes afirst electrically insulating block wrapped by a first array of parallelelectrically conductive wires that span at least a first side of thefirst contact device and a second side of the first contact device.Conductors on the first side of the first contact device are inelectrical contact with the first wetted electrode. A second contactdevice includes a second electrically insulating block wrapped by asecond array of parallel electrically conductive wires that span atleast a first side of the second contact device and a second side of thesecond contact device, wherein wires on the first side of the secondcontact device are in electrical contact with the second wettedelectrode. A conductivity measurement circuit is in electrical contactwith the first wetted electrode via wires on the second side of thefirst contact device and in electrical contact with the second wettedelectrode via wires on the second side of the second contact device. Acontroller is programmed to control the conductivity measurement circuitto pass a current through the fluid between the first wetted electrodeand the second wetted electrode and measure a voltage difference betweenthe first wetted electrode and the second wetted electrode as thecurrent is passed, the controller is further programmed to determine aconductivity of the fluid based on the passed current and the measuredvoltage difference. In variations thereof the third embodiments includeones in which each wire in the first array of parallel electricallyconductive wires and in the second array of parallel electricallyconductive wires is coated with gold.

In variations thereof the third embodiments include ones in which eachadjacent pair of wires in the first array of parallel electricallyconductive wires and in the second array of parallel electricallyconductive wires are electrically isolated from each other by anelectrically insulating material. In variations thereof the thirdembodiments include ones in which the first electrically insulatingblock is made of an elastomeric material. In variations thereof thethird embodiments include ones in which the first electricallyinsulating block is made of silicon, rubber, or synthetic rubber. Invariations thereof the third embodiments include ones in which the firstelectrically insulating bock has a recess on a third side of the firstcontact device, wherein wires spanning the recess are not in contact,over the recess, with the first electrically insulating block. Invariations thereof the third embodiments include ones in which the firstelectrically insulating bock has at least one recess on a fourth side ofthe first contact device, wherein no wires span the fourth side of thefirst contact device over the at least one recess. In variations thereofthe third embodiments include ones in which the conductivity measurementcircuit is in electrical contact with the wires on the second side ofthe first contact device and in electrical contact with the wires on thesecond side of the second contact device via a printed circuit board(PCB).

In variations thereof the third embodiments include ones in which afirst current contact, a second current contact, a first voltagecontact, and a second voltage contact are printed on the PCB, whereinthe first current contact is in electrical contact with a first group ofwires on the second side of the first contact device, wherein the firstvoltage contact is in electrical contact with a second group of wires onthe second side of the first contact device, wherein the second currentcontact is in electrical contact with a first group of wires on thesecond side of the second contact device, wherein the second voltagecontact is in electrical contact with a second group of wires on thesecond side of the second contact device. In variations thereof thethird embodiments include ones in which the first current contact andthe second current contact are electrically connected to two sides of acurrent source in the conductivity measurement circuit, wherein thefirst voltage contact and the second voltage contact are electricallyconnected to two sides of a voltmeter in the conductivity measurementcircuit, wherein the current passed through the fluid between the firstwetted electrode and the second wetted electrode is sourced by thecurrent source, wherein the voltage difference between the first wettedelectrode and the second wetted electrode is measured by the voltmeter.In variations thereof the third embodiments include ones in which thefirst contact device includes a housing that supports the firstelectrically insulating block, wherein the housing is made of anelectrically insulating material. In variations thereof the thirdembodiments include ones in which the first electrically insulatingblock is inserted into a receiving well of the housing. In variationsthereof the third embodiments include ones in which the first side ofthe first contact device and the second side of the first contact deviceat least partially protrude from a first end of the receiving well andsecond end of the receiving well, respectively.

In variations thereof the third embodiments include ones in which theconductivity measurement circuit comprises a permanent electrical deviceof a treatment system, wherein the fluid channel comprises a replaceablecomponent of the treatment system. In variations thereof the thirdembodiments include ones in which the treatment system comprises a fluidcircuit for preparation of a medicament for renal replacement therapy.In variations thereof the third embodiments include ones in which thetreatment system further comprises a water filtration module with afluid circuit and a pump positioned in the fluid circuit to pump watertherethrough, the water filtration module further comprising an inlet,an outlet, and at least one filtration stage has a replaceable filtercomponent, the controller controlling the conductivity measurementcircuit to detect the quality of water upstream of the at least onefiltration stage and output a water quality signal and control the pumpaccordingly. In variations thereof the third embodiments include ones inwhich, when the water quality signal is below a threshold, thecontroller prevents operation of the pump until the replaceable filtercomponent is changed. In variations thereof the third embodimentsinclude ones in which the replaceable filter component includes adeionization filter or an activated carbon filter. In variations thereofthe third embodiments include ones in which the treatment system furthercomprises a medicament preparation device comprising a medicament supplyline that includes at least one concentration sensor station, theconcentration sensor station includes the conductivity measurementsystem and a temperature sensor portion.

In variations thereof the third embodiments include ones in which theconductivity of the fluid is determined based on based on the currentpassed through the fluid, the voltage difference across the first wettedelectrode and the second wetted electrode, and a temperature of thefluid as measured by the temperature sensor portion. In variationsthereof the third embodiments include ones in which a supply of amedicament by at least one pump in the medicament preparation device iscontrolled based on the determined conductivity of the fluid. Invariations thereof the third embodiments include ones in which thetemperature sensor portion includes a flow chamber with a flat surfaceto permit a temperature sensor to be placed against the flat surface ofa predefined sensor of the medicament preparation device.

According to fourth embodiments, the disclosed subject matter includes amedicament preparation system. A fluid circuit has fluid channels withat least one junction, the junction joining a common flow channel thatleads from a water inlet to a medicament outlet. The junction is joinedto a pumping tube segment connected to a source of medicamentconcentrate by a concentrate channel. The at least one junction isoriented in a predefined way relative to the force of gravity. Theconcentrate channel has a chicane that curves sharply up and sharplydown before the concentrate channel meets the common flow channel.

In variations thereof the fourth embodiments include ones in which thechicane's length is no greater than ten internal diameters of theconcentrate channel local to the chicane. In variations thereof thefourth embodiments include ones in which the chicane is immediatelyadjacent a point where the common flow channel and the concentratechannel meet. In variations thereof the fourth embodiments include onesin which the internal cross-sectional flow area of the chicane issmaller than that of the remainder of the concentrate channel. Invariations thereof the fourth embodiments include ones in which thechicane is operable as a trap when fluid of a first density remains inthe concentrate channel while fluid of a second density remains in thecommon flow channel at the junction, where the first density is higherthan the second density, whereby gravity siphoning is prevented. Invariations thereof the fourth embodiments include ones in which thefluid circuit is formed in a rigid structure. In variations thereof thefourth embodiments include ones in which the fluid circuit is formed ina rigid cartridge.

According to fifth embodiments, the disclosed subject matter includes amedical device with a fluid plant that includes a purification element,a patient treatment element, or an admixing element that generates awaste fluid. A drain channel includes means for avoiding foulingincluding one of, an elastic channel and a pump programmed to expand theelastic channel responsively to a pulsation generated by starting andstopping or reversing the pump.

According to sixth embodiments, the disclosed subject matter includes amedical device with a fluid plant that includes a purification element,a patient treatment element, or an admixing element that generates awaste fluid. A drain channel has a biomimetic surface on an interiorsurface thereof, the biomimetic surface is selected to preventattachment or growth of non-flowing material thereon originating from apredefined waste material generated by the purification element, patienttreatment element, or admixing element.

According to seventh embodiments, the disclosed subject matter includesa medical device with a fluid plant that includes a purificationelement, a patient treatment element, or an admixing element thatgenerates a waste fluid. A drain channel is of flexible material, wasteis pumped by a pulsatile pump, the flexible material is selected toexpand and contract sufficiently to prevent the formation of scaling onthe drain channel.

According to eighth embodiments, the disclosed subject matter includes amedical device with a fluid plant that includes a purification element,a patient treatment element, or an admixing element that generates awaste fluid. A drain channel is of expandable material and is connectedto receive the waste fluid. An actuator is in engagement with the drainchannel and adapted to shake or vibrate the drain channel to preventfouling thereof by a predefined material generated by the purificationelement, patient treatment element, or admixing element.

According to ninth embodiments, the disclosed subject matter includes aconductivity sensor with a housing defining an internal fluidcompartment. The housing has openings for receiving electrodes. Theopenings are round. Each of the openings has an inside, closer to theinternal fluid compartment, and an outside portion further from theinterior. The each of the openings has an axial section with a steppedprofile such that the outside portion has a larger diameter than theinside portion. The inside portion has a rim extending axially at leastpartly into the outside portion. The outside portion has at least threespacers extending radially inward toward an axis of a respective one ofthe openings.

In variations thereof the ninth embodiments include ones in which therim is shaped to define an annular trough surrounding a respective oneof the openings. In variations thereof the ninth embodiments includeones in which the annular trough is interrupted by the at least threespacers. In variations thereof the ninth embodiments include ones inwhich the at least three spacers have an axial dimension that is greaterthan a radial dimension thereof. In variations thereof the ninthembodiments include ones in which the at least three spacers each has arounded axial end facing away from the interior. In variations thereofthe ninth embodiments include ones that include an electrode seated ineach of the openings and forming a seal with the rim. In variationsthereof the ninth embodiments include ones in which the annular troughis filled with a cement. In variations thereof the ninth embodimentsinclude ones in which the electrode directly abuts the rim. Invariations thereof the ninth embodiments include ones in which thetrough contains burrs. In variations thereof the ninth embodimentsinclude ones in which the trough contains burrs resulting fromover-confinement of the electrode by the spacers and resulting from apress-fitting operation. In variations thereof the ninth embodimentsinclude ones in which the spacers are sized to over-confine theelectrode such that burrs are produced by press-fitting of theelectrode, the burrs are received by and present in the trough. Invariations thereof the ninth embodiments include ones in which thetrough is continuous such that it encircles each opening. In variationsthereof the ninth embodiments include ones in which the trough isshallower between the spacers than proximate the spacers. In variationsthereof the ninth embodiments include ones in which the trough existsonly proximate the spacers. In variations thereof the ninth embodimentsinclude ones in which the rim has a base and a tip that is narrower thanthe base in axial section, the tip and base is spaced apart along theaxis of the opening. In variations thereof the ninth embodiments includeones in which the cement partly covers the electrode.

According to tenth embodiments, the disclosed subject matter includes amedical treatment system with a fluid circuit that includes at least onejunction where a first fluid line meets a second fluid line. The secondfluid line includes a ceiling protrusion extending out of a ceiling ofthe second fluid line and at least partially blocking the second fluidline. The second fluid line further includes a floor protrusionextending out of a floor of the second fluid line and at least partiallyblocking the second fluid line. The ceiling protrusion is locatedfarther away from the junction than the floor protrusion.

In variations thereof the tenth embodiments include ones that include arigid cartridge that contains the fluid circuit. In variations thereofthe tenth embodiments include ones in which the ceiling protrusion andthe floor protrusion overlap and completely obstruct a central axis ofthe second fluid line, but leave open a tortuous path through the secondfluid line. In variations thereof the tenth embodiments include ones inwhich the second fluid line has a circular cross sectional profile. Invariations thereof the tenth embodiments include ones in which theceiling protrusion and the floor protrusion cooperate to prevent orreduce flow of fluid through the second fluid line into the junction inthe absence of pumping of the fluid when the junction is oriented in apredetermined orientation relative to force of gravity. In variationsthereof the tenth embodiments include ones in which a valley is formedimmediately adjacent to the floor protrusion and below the ceilingprotrusion, and the predetermined orientation is with a center of thevalley is vertically aligned with a center of a lowest portion of theceiling protrusion. In variations thereof the tenth embodiments includeones in which a valley is formed immediately adjacent to the floorprotrusion and below the ceiling protrusion when the fluid junction isoriented in a predefined orientation relative to force of gravity and afluid in the second fluid line is prevented from flowing past the valleydue to gravimetric action. In variations thereof the tenth embodimentsinclude ones that include a first pump that selectively applies pumpingforce to the fluid in the second fluid line and the pumping force causesthe fluid in the second fluid line to flow past the valley into thejunction. In variations thereof the tenth embodiments include ones thatinclude a second pump that selectively applies pumping force to a fluidflowing in the first fluid line. In variations thereof the tenthembodiments include ones in which the fluid flowing in the first fluidline has a lower density than the fluid flowing in the second fluidline. In variations thereof the tenth embodiments include ones in whichthe fluid from the second fluid line is mixed with the fluid from thefirst fluid line when the first and second pumps operate. In variationsthereof the tenth embodiments include ones that include an upperprotrusion at an intersection of a ceiling of the first fluid line andthe ceiling of the second fluid line, the upper protrusion has a taperedcross-sectional shape that extends into a flow channel of the secondfluid line. In variations thereof the tenth embodiments include ones inwhich the upper protrusion reduces turbulence in flow of the fluid inthe first fluid line at the junction. In variations thereof the tenthembodiments include ones in which the upper protrusion is rigid. Invariations thereof the tenth embodiments include ones that include aflap at an intersection of a ceiling of the first fluid line and theceiling of the second fluid line, the flap extending from theintersection of the ceilings toward a side wall of the floor protrusion.In variations thereof the tenth embodiments include ones in which theflap is moveable about a pivot and is biased to be touching the sidewall of the floor protrusion in the absence of external force applied tothe flap. In variations thereof the tenth embodiments include ones inwhich the flap is a live hinge molded at the intersection of theceilings. In variations thereof the tenth embodiments include ones inwhich the flap is movably attached to the pivot with a hinge pin.

According to eleventh embodiments, the disclosed subject matter includesa medical treatment system. A fluid circuit includes a first fluid lineand a second fluid line meeting the first fluid line at an intersection.The first fluid line ceiling intersects the second fluid line ceiling ata first location. A fluid flows along the first fluid line in singledirection. A flap extends from the first location and rests against arim of the second fluid line at the intersection. The flap is biased ina closed position that reduces fluid leakage from the second fluid lineinto the first fluid line in the absence of force that overcomes thebias of the flap.

In variations thereof the eleventh embodiments include ones in which theflap is a living hinge made of a flexible material extending from thefirst location and substantially parallel to a flow direction of fluidflowing in the first fluid line. In variations thereof the eleventhembodiments include ones in which the flap is a rigid piece of materialattached at a pivot location with a hinge pin. In variations thereof theeleventh embodiments include ones that include a fluid pump that pumpsthe fluid in the second fluid line with a pumping force sufficient toovercome the bias of the flap such that the fluid from the second fluidline flows into the intersection when the fluid pump operates.

According to twelfth embodiments, the disclosed subject matter includesa medical device cartridge insertable into a medical treatment device.The cartridge has a rigid frame that provides structure for thecartridge and a fluid circuit supported within the rigid frame. Thefluid circuit includes fluid channels with at least one junction, thejunction joining a common flow channel that leads from a water inlet toa medicament outlet. The junction is joined to a pumping tube segmentconnected to a source of medicament concentrate by a concentratechannel. The at least one junction is oriented in a predefined wayrelative to the force of gravity. The concentrate channel has a chicanethat curves sharply up and sharply down before the concentrate channelmeets the common flow channel. At least one conductivity sensor thatmeasures conductivity of fluid in the fluid circuit, the conductivitysensor includes a housing defining an internal fluid compartment, thehousing has openings for receiving electrodes, the openings being round.Each of the openings has inside portions closer to the internal fluidcompartment and outside portions further from the interior of theinternal fluid compartment, the each of the openings having an axialsection with a stepped profile such that the outside portion has alarger diameter than the inside portion. The inside portion has a rimextending axially at least partly into the outside portion. The outsideportion has at least three spacers extending radially inward toward anaxis of a respective one of the openings.

In variations thereof the twelfth embodiments include ones that includea drain line fluidly attached to a drain channel of the fluid circuit,wherein the drain line conveys waste fluid.

In variations thereof the twelfth embodiments include ones in which thedrain line includes means for reducing fouling in the drain line. Invariations thereof the twelfth embodiments include ones in which thedrain line is made of an elastic material that allows the drain line toexpand and contract and the waste fluid is pumped by a pump withfluctuating pumping pressure that causes the drain line to expand andcontract and thereby reduce attachment of fouling on an interior of thedrain line. In variations thereof the twelfth embodiments include onesthat include a support structure surrounding at least a portion of thedrain line. In variations thereof the twelfth embodiments include onesin which the support structure is more rigid than the drain line. Invariations thereof the twelfth embodiments include ones in which thesupport structure includes a plurality of cut-outs in a body of thesupport structure. In variations thereof the twelfth embodiments includeones that include a holster holding at least a portion of the drainline, the holster mechanically coupled to motor. In variations thereofthe twelfth embodiments include ones in which the motor applies force tothe holster and causes the holster to flex the drain line held by theholster to thereby remove fouling built up inside the drain line. Invariations thereof the twelfth embodiments include ones that includemultiple holsters arranged along at least a portion of the drain line,wherein the motor causes adjacent holsters to move in opposed directionsto flex the drain line held by the holsters.

In variations thereof the twelfth embodiments include ones in which atleast one of the drain line and the drain channel has a biomimeticsurface on an interior surface thereof, the biomimetic surface isselected to prevent attachment or growth of non-flowing material thereonoriginating from a predefined waste material generated by a purificationelement, a patient treatment element, or an admixing element.

According to thirteenth embodiments, the disclosed subject matterincludes a medical device cartridge insertable that is into a medicaltreatment device. The cartridge has a fluid circuit that includes fluidchannels with at least one junction, the junction joining a common flowchannel that leads from a water inlet to a medicament outlet. Thejunction is joined to a pumping tube segment connected to a source ofmedicament concentrate by a concentrate channel. The at least onejunction is oriented in a predefined way relative to the force ofgravity. The concentrate channel has a chicane that curves sharply upand sharply down before the concentrate channel meets the common flowchannel. At least one conductivity sensor measures conductivity of fluidin the fluid circuit. The conductivity sensor includes a housingdefining an internal fluid compartment. The housing has openings forreceiving electrodes. The openings are round. Each of the openings hasinside portions closer to the internal fluid compartment and outsideportions further from the interior of the internal fluid compartment.The each of the openings has an axial section with a stepped profilesuch that the outside portion has a larger diameter than the insideportion. The inside portion has a rim extending axially at least partlyinto the outside portion. The outside portion has at least three spacersextending radially inward toward an axis of a respective one of theopenings. A fluid channel has a first wetted electrode and a secondwetted electrode configured to directly contact a fluid flowing in thefluid channel. A first contact device includes a first electricallyinsulating block wrapped by a first array of parallel electricallyconductive wires that span at least a first side of the first contactdevice and a second side of the first contact device, wherein conductorson the first side of the first contact device are in electrical contactwith the first wetted electrode. A second contact device includes asecond electrically insulating block wrapped by a second array ofparallel electrically conductive wires that span at least a first sideof the second contact device and a second side of the second contactdevice, wherein wires on the first side of the second contact device arein electrical contact with the second wetted electrode. A conductivitymeasurement circuit in electrical contact with the first wettedelectrode via wires on the second side of the first contact device andin electrical contact with the second wetted electrode via wires on thesecond side of the second contact device. A controller is programmed tocontrol the conductivity measurement circuit to pass a current throughthe fluid between the first wetted electrode and the second wettedelectrode and measure a voltage difference between the first wettedelectrode and the second wetted electrode as the current is passed, thecontroller is further programmed to determine a conductivity of thefluid based on the passed current and the measured voltage difference.

Features of the disclosed embodiments may be combined, rearranged,omitted, etc., within the scope of the disclosed subject matter toproduce additional embodiments. Furthermore, certain features maysometimes be used to advantage without a corresponding use of otherfeatures. It is, thus, apparent that there is provided, in accordancewith the present disclosure, a needle guard and associated manufactures,components, systems, and methods of use. Many alternatives,modifications, and variations are enabled by the present disclosure.While specific embodiments have been shown and described in detail toillustrate the application of the principles of the disclosure, it willbe understood that the disclosed subject matter may be embodiedotherwise without departing from such principles. Accordingly,Applicants intend to embrace all such alternatives, modifications,equivalents, and variations that are within the spirit and scope of thepresent disclosure.

In any of the embodiments described herein, including the claims, theterms compliant multiconductor element elastomeric contact element,elastomeric contact, and elastomeric contact insert may be interchangedto form alternative embodiments. In any of the embodiments, the termscompliant multiconductor element, elastomeric contact insert, orelastomeric contact may be loosely held to an electrode by a housingsuch as housing 752. In embodiments, the housing may be a flexiblematerial such as soft plastic, rubber, silicone, elastomer, or othercompliant material. The housing (e.g., 752) may be attached to thecartridge support 556 or equivalent conductivity measurement channelportion but not directly affixed to the compliant multiconductor elementand elastomeric contact insert. That is, the housing may hold theelement/insert in place over the electrode but permit it to moverelative to the electrode so that it can be firmly pressed against it.

It will be appreciated that the modules, processes, systems, andsections described above can be implemented in hardware, hardwareprogrammed by software, software instruction stored on a non-transitorycomputer readable medium or a combination of the above. For example, amethod for controlling the generating of a medicament or treatment fluid(or methods therewithin such as for the generating of purified water)can be implemented, for example, using a processor configured to executea sequence of programmed instructions stored on a non-transitorycomputer readable medium. For example, the processor can include, butnot be limited to, a personal computer or workstation or other suchcomputing system that includes a processor, microprocessor,microcontroller device, or is comprised of control logic includingintegrated circuits such as, for example, an Application SpecificIntegrated Circuit (ASIC). The instructions can be compiled from sourcecode instructions provided in accordance with a programming languagesuch as Java, C++, C#.net or the like. The instructions can alsocomprise code and data objects provided in accordance with, for example,the Visual Basic™ language, LabVIEW, or another structured orobject-oriented programming language. The sequence of programmedinstructions and data associated therewith can be stored in anon-transitory computer-readable medium such as a computer memory orstorage device which may be any suitable memory apparatus, such as, butnot limited to read-only memory (ROM), programmable read-only memory(PROM), electrically erasable programmable read-only memory (EEPROM),random-access memory (RAM), flash memory, disk drive and the like.

Furthermore, the modules, processes, systems, and sections can beimplemented as a single processor or as a distributed processor.Further, it should be appreciated that the steps mentioned above may beperformed on a single or distributed processor (single and/ormulti-core). Also, the processes, modules, and sub-modules described inthe various figures of and for embodiments above may be distributedacross multiple computers or systems or may be co-located in a singleprocessor or system. Exemplary structural embodiment alternativessuitable for implementing the modules, sections, systems, means, orprocesses described herein are provided below.

The modules, processors or systems described above can be implemented asa programmed general purpose computer, an electronic device programmedwith microcode, a hard-wired analog logic circuit, software stored on acomputer-readable medium or signal, an optical computing device, anetworked system of electronic and/or optical devices, a special purposecomputing device, an integrated circuit device, a semiconductor chip,and a software module or object stored on a computer-readable medium orsignal, for example.

Embodiments of the method and system (or their sub-components ormodules), may be implemented on a general-purpose computer, aspecial-purpose computer, a programmed microprocessor or microcontrollerand peripheral integrated circuit element, an ASIC or other integratedcircuit, a digital signal processor, a hardwired electronic or logiccircuit such as a discrete element circuit, a programmed logic circuitsuch as a programmable logic device (PLD), programmable logic array(PLA), field-programmable gate array (FPGA), programmable array logic(PAL) device, or the like. In general, any process capable ofimplementing the functions or steps described herein can be used toimplement embodiments of the method, system, or a computer programproduct (software program stored on a non-transitory computer readablemedium).

Furthermore, embodiments of the disclosed method, system, and computerprogram product may be readily implemented, fully or partially, insoftware using, for example, object or object-oriented softwaredevelopment environments that provide portable source code that can beused on a variety of computer platforms. Alternatively, embodiments ofthe disclosed method, system, and computer program product can beimplemented partially or fully in hardware using, for example, standardlogic circuits or a very-large-scale integration (VLSI) design. Otherhardware or software can be used to implement embodiments depending onthe speed and/or efficiency requirements of the systems, the particularfunction, and/or particular software or hardware system, microprocessor,or microcomputer being utilized. Embodiments of the method, system, andcomputer program product can be implemented in hardware and/or softwareusing any known or later developed systems or structures, devices and/orsoftware by those of ordinary skill in the applicable art from thefunction description provided herein and with a general basic knowledgeof control systems, sensors, electromechanical effecters and/or computerprogramming arts.

Moreover, embodiments of the disclosed method, system, and computerprogram product can be implemented in software executed on a programmedgeneral-purpose computer, a special purpose computer, a microprocessor,or the like.

It is, thus, apparent that there is provided, in accordance with thepresent disclosure, medicament preparation and treatment devices,methods, and systems. Many alternatives, modifications, and variationsare enabled by the present disclosure. Features of the disclosedembodiments can be combined, rearranged, omitted, etc., within the scopeof the disclosed subject matter to produce additional embodiments.Furthermore, certain features may sometimes be used to advantage withouta corresponding use of other features. Accordingly, Applicant intends toembrace all such alternatives, modifications, equivalents, andvariations that are within the spirit and scope of the present disclosedsubject matter.

The invention claimed is:
 1. A method for measuring a conductivity in afluid flowing in a fluid channel, comprising: contacting a flowing fluidwith two electrodes spaced apart across a portion of the fluid channel;and contacting each of the two electrodes to a current source contactand a voltage measuring contact by creating a continuity between each oftwo respective portions of the each of the two electrodes and arespective one of the current source and voltage measuring contacts withmultiple conductors located on a surface of a resilient insulatingmember, wherein the creating the continuity includes squeezing theresilient insulating member for each of the two electrodes between theeach of the two electrodes and a respective combination of the currentsource and voltage measuring contacts.
 2. The method of claim 1, whereinthe resilient insulating member and the multiple conductors form a Zebraconnector.
 3. The method of claim 1, wherein the contacting includesattaching the resilient insulating member to the fluid channel.
 4. Themethod of claim 1, wherein the contacting includes attaching theresilient insulating member to the fluid channel loosely such that theresilient insulating member can move in a limited range along an axisperpendicular to a surface of said each of the two electrodes.
 5. Themethod of claim 1, wherein the contacting includes attaching theresilient insulating member to the fluid channel loosely by a housingsuch that the resilient insulating member can move in a limited rangealong an axis perpendicular to a surface of said each of the twoelectrodes.
 6. The method of claim 1, wherein the contacting includesattaching the resilient insulating member to the fluid channel looselyby a housing partially surrounding the resilient insulating member suchthat the resilient insulating member can move in a limited range alongan axis perpendicular to a surface of said each of the two electrodes.7. The method of claim 6, further comprising measuring a resistance ofelectrical continuity between the voltage measuring contact and thecurrent source contact to detect contact resistance.
 8. The method ofclaim 6, further comprising performing Kelvin sensing by measuring anelectrical impedance between the two electrodes by driving currentbetween the two electrodes while measuring a voltage between them thetwo electrodes.
 9. The method of claim 6 wherein the resilientinsulating member and the multiple conductors constitute an elastomericcontact insert or a compliant multiconductor element.
 10. A conductivitymeasurement system, comprising: a replaceable fluid circuit with atleast two electrodes forming a part of a wall of a fluid channel suchthat each of the at least two electrodes has a wetted side facing aninterior of the fluid channel and a contact side opposite the wettedside; flexible electrically-conducting elements attached to the fluidchannel each with at least one conductor thereof facing the contact sideof a respective one of said at least two electrodes; a medicamentproportioning module having a pair of electrical contacts connected to acurrent source and a voltage sensor for each of the at least twoelectrodes; the medicament proportioning module being configured toreceive the replaceable fluid circuit such that each of the flexibleelectrically-conducting elements is forced between the respective one ofthe at least two electrodes and a respective one of the pairs ofelectrical contacts.
 11. A conductivity measurement system, comprising:a fluid channel with a first wetted electrode and a second wettedelectrode configured to directly contact a fluid flowing in the fluidchannel; a first contact device including a first electricallyinsulating block wrapped by a first array of parallel electricallyconductive wires that span at least a first side of the first contactdevice and a second side of the first contact device, wherein conductorson the first side of the first contact device are in electrical contactwith the first wetted electrode; a second contact device including asecond electrically insulating block wrapped by a second array ofparallel electrically conductive wires that span at least a first sideof the second contact device and a second side of the second contactdevice, wherein wires on the first side of the second contact device arein electrical contact with the second wetted electrode; a conductivitymeasurement circuit in electrical contact with the first wettedelectrode via wires on the second side of the first contact device andin electrical contact with the second wetted electrode via wires on thesecond side of the second contact device; and a controller programmed tocontrol the conductivity measurement circuit to pass a current throughthe fluid between the first wetted electrode and the second wettedelectrode and measure a voltage difference between the first wettedelectrode and the second wetted electrode as the current is passed, thecontroller being further programmed to determine a conductivity of thefluid based on the passed current and the measured voltage difference.12. The system of claim 11, wherein each wire in the first array ofparallel electrically conductive wires and in the second array ofparallel electrically conductive wires is coated with gold.
 13. Thesystem of claim 11, wherein each adjacent pair of wires in the firstarray of parallel electrically conductive wires and in the second arrayof parallel electrically conductive wires are electrically isolated fromeach other by an electrically insulating material.
 14. The system ofclaim 11, wherein the first electrically insulating block is made of anelastomeric material.
 15. The system of claim 11, wherein the firstelectrically insulating block is made of silicon, rubber, or syntheticrubber.
 16. The system of claim 15, wherein the first electricallyinsulating bock has a recess on a third side of the first contactdevice, wherein wires spanning the recess are not in contact, over therecess, with the first electrically insulating block.
 17. The system ofclaim 16 wherein the first electrically insulating bock has at least onerecess on a fourth side of the first contact device, wherein no wiresspan the fourth side of the first contact device over the at least onerecess.
 18. The system of claim 16 wherein the conductivity measurementcircuit is in electrical contact with the wires on the second side ofthe first contact device and in electrical contact with the wires on thesecond side of the second contact device via a printed circuit board(PCB).